The Articles attached are from aviation magazines you are familiar with. They all deal with safe flying and general interest. You may have already read them, but we thought it would be worthwhile to add them on the site.
This is an article that lets us know how far the GPS system has come AOPA Pilot Magazine December 2009 Volume 52 / Number 12
Turbine Pilot: RNP primer
Understanding Next-Gen approaches
By Marc K. Henegar
AAA.I’m flying an Alaska Airlines Boeing 737 down the Gastineau Channel, getting ILS-style guidance to a runway I could not see yet if it were clear and a million. The approach end of Juneau International Airport’s Runway 26 is at 11 o’ clock and seven miles, over there behind Douglas Island. Now, calling where I am a channel is a bit benign—it’s actually a fjord only a few hundred yards wide at the bottom, rising to parallel ridgelines more than 3,000 feet high and barely more than a mile wide in some places. And I’m not over the channel, I’m in it; the ridgelines are well above me on both sides of the airplane.
I’m making turns every few miles in the channel and my final turn to align with the runway is about 40 degrees, rolling wings level at about 500 feet agl—and I still can’t see the airport. I break out right at the minimums of 337 feet msl and a mile, on the centerline, and land. Sound unusual? This is a typical day flying a typical RNP (required navigational performance) approach in southeast Alaska—to a runway that has no other approach.
What is RNP?
Simply put, RNP is RNAV on steroids. In general terms, RNP is a statement of navigation performance necessary for a defined operation within a defined airspace. What sets RNP apart from RNAV is on-board monitoring and alerting, letting you know if the airplane’s actual navigation performance (ANP) meets approach requirements. It’s pretty simple—if ANP (actual) is greater than RNP (required) then you’re good.
Instrument approaches using RNP are classified as RNAV approaches, so the approach plate header bears the “RNAV (RNP)” label. But that’s where the similarity with RNAV (GPS) approaches ends. RNP operations earn their tighter tolerances and accuracies by adding assurances that go beyond on-board monitoring and alerting. These include:
•Special aircraft and aircrew authorization required (SAAAR). This means the aircrew must have training in RNP operations, and airplane must have the proper equipment.
•WAAS (Wide Area Augmentation System) capability. WAAS GPS receivers use both satellites and ground stations to come up with position accuracies up to five times greater than those displayed on non-WAAS GPS receivers. WAAS also permits glideslope-like vertical guidance on LNAV/VNAV and LPV (localizer performance with vertical guidance) approaches.
•Dual GPS and FMS installations. This guards against any equipment-originated single point of failure that could cause a loss of guidance. The lowest RNP values require dual autopilots.
•More accurate altimeters, and vertical navigation (VNAV) based on barometric altimetry.
•An inertial reference unit (IRU). This serves as a backup in case a GPS satellite signal is lost. The backup IRU becomes vital, for example, if a missed approach is caused by loss of a GPS signal.
We typically define an RNP approach by its RNP “value,” which is normally expressed as a lateral distance in nautical miles from the centerline—as in “that’s an RNP 0.10 approach.” (There are also RNP 0.3 approaches.) The airplane is required to be within that value, meaning within .1nm or .3 nm either side of the course centerline, at least 95 percent of the time. However, data collected shows performance to be far more accurate than required and on centerline pretty much all the time.
Operation within that 1 times RNP containment is considered to be normal operation—pilots are required to execute a missed approach if they go beyond that. Outside of that, there is an additional buffer zone of 1 times RNP that separates aircraft from terrain. For example, normal operation for an RNP 0.10 approach path width would be 608 feet (1 times RNP) on each side of centerline and any terrain would be at least 1,216 feet (2 times RNP) away from centerline. To meet RNP qualifications, the airplane is required to be between the centerline and that 2 times RNP boundary 99.999 percent of the time.
RNP is not dependent upon a certain source, such as a VOR or a localizer, but is a measure of total system performance. In theory, no one cares how you got it but in reality RNP is based almost exclusively on GPS. There is no RNAV approximation of position using VOR radial/DME triangulation that is robust enough to provide the RNP for most terminal-based operations.
The bottom line is that RNP allows us to build approaches and departures we just couldn’t build before GPS. It offers the flexibility of varying glide paths and curved legs of varying radius and length, a huge benefit for procedure design. So, if a rock is in the way, just go around it.
RNP and WAAS
From a pilot’s perspective, both WAAS and RNP approaches look and fly like an ILS. There is a “localizer” (LNAV) and a “glideslope” (VNAV) and both use GPS as the primary navigation source.
The main difference between WAAS and RNP is the GPS signal itself. WAAS enhances the signal through differential correction (using an additional satellite) to a typical accuracy of about three meters, while RNP uses unenhanced GPS, with a typical accuracy of about 15 meters. This results in a WAAS airplane having a more accurate fix on its location than an RNP airplane.
While WAAS is more accurate, RNP has more design flexibility. Generally, if terrain is not a consideration, WAAS will usually result in lower minima than RNP to a given runway. If terrain is a consideration, RNP will usually result in lower minima to a given runway than WAAS—if a WAAS approach could even be built.
WAAS uses an electronic glidepath calculated by GPS position, where RNP uses a barometric (sometimes called BARO VNAV) glidepath that is affected by temperature and altimetry. That is why RNP procedures require current altimeter settings and sometimes have temperature limits.
WAAS sees more widespread use than RNP. In addition to the 11 RNP procedures that Alaska Airlines developed, there are now more than 100 public RNP approaches in the United States, and the FAA is developing about 35 new RNP approaches a year. Most RNP approaches have minima lines associated with several different RNP values for days when satellite performance is less than stellar. With a full constellation of satellites—and if their owner, the Department of Defense, keeps accuracy high by leaving selective availability off—those days are rare.
By contrast there are almost 1,400 WAAS LPV approaches. For the most part, RNP is flown by the airlines, as well as recent-model high-end business jets. WAAS is flown by a much larger, ever-increasing group of general aviation airplanes equipped with WAAS-approved GPS receivers. WAAS-enabled approach capability is quickly becoming mainstream in airplanes ranging from the smallest piston singles to the biggest business jets. One important distinction, at least for the moment, is that RNP approaches can be done anywhere, while WAAS approaches are limited to the range of the WAAS satellites.
Required equipment
FAA Advisory Circular AC90-101 outlines equipage, operational, and training requirements for RNP approaches. You only need one approved box to fly WAAS approaches; for RNP you need dual flight management computers, inertial reference systems, GPS receivers, air data computers, a radio altimeter, and more. You might be wondering if you get any relief from RNP equipage for being WAAS-equipped—but you don’t, at least not yet.
A more “basic” RNP is being discussed that would lower the barrier of entry while hopefully not removing all of its utility. Beyond that, public RNP departure criteria are being developed, along with studies to examine the viability of dual-stream RNP approaches to parallel runways and decision altitudes in turns. As the voice of general aviation, AOPA is involved in these efforts on your behalf.
The pilot’s view
“Anchorage Center, Alaska Seven-Six over Annette Island at Flight Level 350.”
“Alaska Seven-Six, Anchorage Center. Good afternoon, maintain 7,000 feet until on a published portion of the approach, cleared for the RNP Runway 26 approach to the Juneau Airport. Contact Juneau Tower over MARMN, have a nice day.” That and a landing clearance are all I will hear between 35,000 feet and the runway.
The first time I heard that I nearly choked. What do you mean, cleared for the approach? How do I get from 35,000 feet to the ground on my own without ATC? Well, with RNP, the airplane has a defined path all the way from cruise to the runway, so we rely less on ATC. This reduces communications workload, as well as frequency congestion. And because of an RNP approach path’s higher level of accuracy, I get to fly to minimums that are far lower than those available with more traditional approach procedures
If I were not flying RNP to Juneau, chances are I’d be flying an NDB, VOR, or LDA nonprecision approach and choosing between a tailwind or circling to land on a short runway with no safety area in ugly weather. And, if I miss or get unstable and have to go around, my lateral guidance may be provided by an NDB that is swinging like an ape from a tree.
Instead of worrying about these issues, with RNP, I just fly. Sometimes I have course-deviation indicators like those you see when you fly RNAV or ILS approaches. Sometimes I don’t, which means I have to pick up lateral and vertical deviation in textual form off the flight management system display by my knee. I see lateral deviation in hundredths of miles (each hundredth is 60 feet) left or right of centerline and I see vertical deviation in feet above or below path. It’s a little different in the beginning, but you get used to it.
Yes, there are nice days when I turn all the automation off and just hand-fly a pattern to a runway—and I love that. But those opportunities are few and far between in Alaska. So, I am glad to have a tool in my aviation toolbox that will get me to the runway threshold stable, on speed, on centerline, and ready to land. It’s also immensely helpful to have an RNP-defined missed approach procedure with both lateral and vertical guidance should something not go as planned. But missing an approach due to low weather is less likely with RNP. RNP approaches have lower minimums, so what would have been a “miss” with a plain-Jane RNAV GPS, VOR, or other nonprecision approach will often be what’s called an “RNP save” arrival.
Alaska Airlines pioneered it in the mid-1990s, and RNP is now in use in many nations. But an expansion of its capabilities and uses is in the offing, beginning with more RNP approaches in the United States. The FAA’s Next Generation Air Transportation System (NextGen) timetable calls for RNP to be used for reducing traffic separation on oceanic routes starting in 2010. Reduced domestic en route separation using RNAV and RNP is planned for implementation in 2013. By 2020, the goal is to realize international harmonization of RNP and satellite-based communications under a larger plan called the Future Air Navigation System (FANS). FANS was adopted by the International Civil Aviation Organization (ICAO), with the goal of boosting capacity and reducing workload by integrating communications, navigation, and surveillance functions. There’s a lot to gain. From a capacity point of view, RNP doesn’t define approach path or airway lateral dimensions in terms of nautical miles; it defines them in tenths of miles. This means each airplane needs less separation space. The result: more airplanes can safely navigate within a given volume of airspace. But FANS promises more. Automatic position reporting, and reporting of critical flight parameters using Automatic Dependent Surveillance technology will be possible. So will controller-pilot datalink communications, whereby clearances and other communications are conducted using text messages, which will reduce pilot and controller workload—and potential misunderstandings.
It seems we are nibbling at the edges of a revolution in flying. Those of us lucky enough to fly using RNP should fly more precisely, efficiently, and safely—and it shouldn’t be long in coming.
Marc K. Henegar is a captain for a national airline.
RNP in sight
Avionics manufacturers have wasted no time in keeping up with RNP technology. The latest strategies have been to merge RNP capability with increasingly sophisticated primary flight displays (PFDs). The result is a wealth of graphic information, right before the pilot’s eyes. Both Honeywell’s Primus Epic and Rockwell Collins’ Pro Line Fusion avionics suites, for example, now can merge synthetic vision imagery with traditional flight guidance data. The Fusion adds infrared imagery to its PFDs, and the Epic will soon add that feature as well.
It may be night, or you might be in clouds, but with synthetic vision on the PFD, it’s always day-VFR, complete with terrain depiction. And there are plenty more capabilities with Honeywell’s latest upgrades.
The Primus Epic platform is used in Gulfstream’s G350, G450, G500, and G550. It’s also in the Cessna Sovereign, the Hawker 4000, the Emivest SJ30 (formerly the Sino-Swearingen SJ30), and in the Falcons 900EX, 2000EX, and 7X. Gulfstream calls its customized version of the Epic “PlaneView.” Falcon Jet Corporation calls its latest Epic suite the “EASy II.” Bombardier calls the ProLine Fusion “Global View” in its Global Express XRS and Global 5000 large-cabin, long-range business jets.
The list of features is too lengthy to detail in this space, but the EASy II package adds several significant upgrades, some of which are optional. Synthetic vision (Falcon Jet calls it “SmartView”) tops the list, but the addition of RNP 0.3 capability as standard is a big leap forward, as is SmartRunway (a runway awareness and advisory system [RAAS] with aural cuing to warn against approaches that are too high, low, or if the airplane’s configuration is improper), and autothrottle arming on the ground.
RNP 0.1 capability is another option. This provides a more accurate flight path on approach; a fully-deflected course deviation indicator needle amounts to just .1 nm–or about 608 feet–from the course centerline. WAAS LPV and ADS-B capability are other options, as is an automatic descent mode (ADM), which commands an emergency descent in case of depressurization. XM WX datalink weather and WAAS LPV are also available, and so are electronic charts.
There are even provisions for adding Future Air Navigation System-1A (FANS-1A) functions, such as controller-pilot datalink communications (CPDLC). Under CPDLC, communications between cockpit and controllers is via text messages.
—Thomas A. Horne
This is an article taken from the same issue of AOPA Magazine (December 2009) It reviews the designations of icing intensities.
Wx Watch: Icing Intensities
‘Trace’ to ‘severe’ – what’s in a name?
By Thomas A. Horne
A A A Let’s get something out of the way right up front: Avoid icing conditions if at all possible, and escape them immediately should you encounter icing. It’s as simple as that.
In actual practice, however, there can be complications. A front speeds up, the weather changes, and your strategizing may not move as fast as those thickening clouds you’ve been trying to dodge for the past 20 minutes. Soon, you’re in the soup. Of course, you learned about the front during your preflight weather briefing. And let’s say you noticed pireps (pilot reports) of “trace” to “light” icing from airplanes flying in the frontal zone. Does this mean that your risks are lower than if the pireps mentioned “moderate” icing? Not by any means.
The measurement and effects of icing intensity levels have always been a controversial subject. Today, we use the terms trace, light, moderate, and severe to indicate the rate and extent of ice accretions. (The terms rime, clear, mixed, and supercooled large-droplet [SLD] refer to the type of ice accumulation, and do not imply rate, effect, or extent of an icing situation.)
The distinctions between the intensity levels can mean a lot. They inform other pilots of the potential hazard, and give meteorologists information to help confirm or refute assumptions they might have made in previous forecasts. A pirep given to air traffic control (ATC)—and reports of hazardous or unforecast weather as required per FAR 91.183—can pave the way to a helpful vector, climb, or descent away from the ice.
The Aeronautical Information Manual (AIM), in Section 7-1-21, describes the current intensity levels to use when reporting icing conditions.
Trace icing
Trace icing sounds pretty benign. The AIM says that this intensity level can be reported when ice becomes perceptible. It goes on to say that the rate of accumulation is slightly greater than the rate of sublimation. Even though this implies a steady buildup over time, the AIM states that ice protection equipment “is not utilized unless [trace levels of icing are] encountered for an extended period of time (over one hour).”
Light icing
The potential for trouble kicks up a notch with light ice accumulations. Light ice, in the AIM, means that the rate of accumulation may create a problem if flight is continued past one hour. The definition goes on to say that occasional use of ice-protection equipment removes or prevents light ice, and that this level of icing “does not present a problem” if deicing/anti-icing equipment is used. Moderate icing
In moderate icing, the AIM says, even short encounters become potentially hazardous, and that “the use of deicing/anti-icing equipment or flight diversion is necessary.”
Severe icing
Severe icing—now we have a serious problem. The AIM says that ice protection equipment cannot “reduce or control the hazard. Immediate flight diversion is necessary.”
Definition dilemmas
For years, these icing intensity levels have been criticized. One argument cites that icing intensity is aircraft-dependent. In other words, the intensity categories don’t apply equally to all airplanes. A big, fat Piper Aztec wing accumulates ice at a lower rate than a Mooney’s slender wing cross-section. That’s because ice accretes much more quickly on small-radius projections—which also explains why ice first appears on antennas, rivet heads, elevators, and other small-radius protuberances. So just because a Boeing 737 reports light icing doesn’t mean that your Cessna 182 will experience the same. What’s light icing for one airplane can be moderate to severe for others. In short, we simply don’t know how the intensity reported by one airplane relates to intensities on others.
Notice also that the intensity definitions always refer to ice-protection equipment. In fact, most light general aviation airplanes do not have ice protection. (The exception might be a solitary heated pitot tube.) So, some say that the intensity levels really don’t apply to unprotected aircraft—if you don’t have ice protection, how can you know what its effect might be in your current situation? Other than as suggestions regarding the nature of the icing environment, of what operational value are today’s icing intensity levels?
Furthermore, the AIM makes no distinction between ice protection equipment that’s been installed piecemeal under a supplemental type certificate (STC) and the equipment complement installed in an airplane that’s been certified for flight into known icing (FIKI) conditions. There’s a big, big difference between an airplane that’s fitted solely with aftermarket deice boots and a heated windshield plate, and one that’s met the sort of in-flight testing and simulations required for FIKI approval.
Finally, the warnings about severe icing don’t seem to apply to certain turboprops meeting the requirements of Special Federal Aviation Regulation (SFAR) number 23, section 34, which calls for FIKI certification. These rules affect turboprops with more than 10 seats, and operated under FAR Part 135—commuter and on-demand air charter and air taxi operations. The letter of the law, in FAR Part 91.527, says that these SFAR 23 airplanes can operate in known or forecast severe icing conditions. So what happened to the severe intensity’s warning that ice protection equipment can’t fight off ice?
Intensity through the years
How did we inherit today’s icing intensity scale? Good question, with some revealing answers. For a complete rundown, see Richard K. Jeck’s technical paper on the FAA’s Web site.
The first intensity scale was developed in the 1940s, but not for airplanes. It was designed for reporting the ice accretions at the weather observatory at the summit of Mount Washington, New Hampshire! It was assumed that airplanes flying through similar conditions would build ice at the same rate, based on an airplane flying at 200 mph/174 knots.
In 1956, the U.S. Air Force came up with an intensity scale that factored liquid water content (LWC, or the number of grams of water per cubic meter) and distance traveled into the equation. It’s worth mentioning that the 1956 scale used a small, one-half-inch-diameter probe for making the ice-over-distance measurements—a bad idea, considering that the probe’s ice-collection efficiency served to overstate the accumulation rate. In addition, the Air Force scale was aimed at typical fighter aircraft.
The intensity scale was altered again by an interagency committee in 1964. It replaced the “severe” with the “heavy” category of ice accretion. In 1968, the current intensity scale came out.
But the problems mentioned previously persisted—chiefly, that ice accretion rates vary by aircraft type and model. An FAA Inflight Icing Plan was drawn up in 1998, and a working group came up with a suggested renaming of icing intensities. The group sought to emphasize and quantify each icing intensity’s level of effect. Specific airspeed losses, climb-rate deteriorations, power requirements, and control input and vibration responses were listed. The table above shows the proposed scheme.
However, a big problem remains with this approach. In order to be meaningful, each airplane would have to undergo extensive in-flight testing to quantify the performance losses and other effects. That would be a huge task. Perhaps that’s why the plan has yet to be adopted.
All of this bureaucratic evolution is interesting, but it shouldn’t distract us from following the avoid-or-immediate-escape admonition that I stated at the beginning of this article. Besides, there’s a big trap in buying into the intensity levels lock, stock, and barrel. “Light” icing, for example, can be a transient thing. Stay in light icing long enough, and you’ve got severe icing.
E-mail the author at tom.horne@aopa.org.
Effect on Aircraft—From the 1998 FAA Inflight Icing Plan
Aircraft Effect (AE) 1. Speed 2. Power 3. Climb 4. Control 5. Vibration
Level 1 Less than 10 knots loss Less than 10% increase required No effect or less than 10% loss No effect No effect
Level 2 10 to 19 knots loss 10% to 19% increase required 10% to 19% loss rate of climb No effect No effect
Level 3 20 to 39 knots loss 20% to 39% increase required 20% or more loss rate of climb Unusually slow or sensitive response from control input Controls may have a slight vibration
Level 4 40 knots loss or more Not able to maintain speed Not able to climb Little or no response to control input May have intense buffet and/or vibration
1. Loss of airspeed because of aircraft icing, based on indicated airspeed maintained prior to encountering ice.
2. Additional power required to maintain aircraft speed/performance.
3. Estimated reduction in rate of climb because of aircraft icing.
4. Effect of icing to aircraft control inputs.
5. Vibration or buffet that may be sensed through the aircraft controls (not intended to refer to unusual propeller vibration for airplanes so equipped in icing conditions).
A A A Related Links
Aviation Weather
November 2011 Volume 54 / Number 1
200 feet, lights in sight
Why you may not see the runway
By Neil Singer
October 2011
Turbine Pilot Contents
- Turbine Intro: Twin Turboprop for the Masses: Putting value into turbine operations
- Jet or turboprop? This owner decided to keep his Piper Cheyenne II XL
- 200 Feet, Lights in Sight: Low ILS approaches call for a tricky transition
- Consolidation of Knowledge: Ways to avoid post-grad brain dump
“Approach lights in sight, continue” is a callout heard during every two-pilot jet simulator session, yet generally unfamiliar to pilots transitioning from piston aircraft. Why? The reliability and capability of jet aircraft are so great that they are often flown into weather conditions a pilot wouldn’t take a piston aircraft. Very low visibility conditions are one such example.
The lowest ceiling and visibility authorized for a Category I ILS (the only category most GA aircraft are capable of flying) are a 200-foot decision height (DH) and a 1,800-foot runway visual range (RVR), or roughly one-quarter-mile visibility. Given that a 3-degree glideslope descends approximately 300 feet per nm of forward travel, an aircraft at a 200-foot DH will be two-thirds of a nm, or about 4,000 feet, from the point where the glideslope intersects the runway. As glideslopes are set to lead to a touchdown zone 1,000 feet down the runway, this puts the aircraft 3,000
feet from the runway threshold.
You may have the needles centered at an ILS decision height, but given the dynamics of a 3-degree descent, you may not see the runway touchdown zone. That’s where FAR 91.175 kicks in. With the approach lights in sight, you can legally continue the approach, using the lights for guidance to the runway.
Since the legal visibility may be as low as 1,800 feet it is possible for the pilot to be in a situation where the runway 3,000 feet away may not be visible at DH. Depending on the type of approach lights, they extend from 1,400 feet to 3,000 feet from the threshold of the runway—they extend far enough towards an aircraft at DH that they will be the only lights in view on a minimums approach.
FAR 91.175 states that an aircraft may continue an approach below DH without the runway in sight, if the aircraft has the approach lights in sight “…except that the pilot may not descend below 100 feet above the touchdown zone elevation using the approach lights as a reference unless the red terminating bars or the red side row bars are also distinctly visible and identifiable.”
The red lights do not exist at most smaller airports, so effectively the pilot must have the runway in sight at 100 feet to continue. At 100 feet above touchdown zone elevation (TDZE), the aircraft is now one-third of a nm, or 2,000 feet, from touchdown point, and thus 1,000 feet from the runway threshold. Even with lowest case 1800 RVR, the pilot should have no trouble acquiring the runway with this geometry. If a runway has no approach lights, or if the approach lights are out of service, the minimum landing visibility jumps to 4,000 RVR, as without lights the runway itself must be visible at DH.
Knowing what can be expected visually at minimums is an important part of the approach briefing for a very low IFR approach. Most of the time, if an airport is reporting less than 3,000 RVR, the pilot should be anticipating a transition from 200 feet to 100 feet referencing the approach lights alone. This means controlling the airplane mainly by reference to instruments, with very quick peeks out the window. Understandably this can make for a busy 100 feet of descent, even more so for a single-pilot operation; anticipating the workload can help reduce the stress of a difficult transition.
———- Forwarded message ———-
From: Gillard
Date: Mon, May 14, 2012 at 7:20 AM
Subject: Fwd: The Truculent Turtle
To:
Great story.
Truculent Turtle
Great story.
Hard to believe that they could squeeze 55 hours out of the beast.!?!
This is a rather long and interesting story about a Navy P-2 that flew non-stop from Perth Australia to Columbus, Ohio in 1946.
More than 11,000 miles with more than 55 hours in the air…
The oxidized Lockheed ‘ Truculent Turtle ‘ had been squatting next to a Navy Air Station’s main gate, completely exposed to the elements and getting ragged around the edges. Finally recognizing the Turtle’s singular historic value to aviation, it was moved to Pensacola to receive a badly required and pristine restoration. It is now – gleamingly hanging – from the National Naval Aviation Museum’s ceiling where it earned its distinction.
Taxiing tests demonstrated that its Lockheed P2V-1’s landing gear might fold while bearing the Turtle’s extreme weight before carrying it airborne. And during taxi turns its landing gear struts could fail carrying such a load. For that reason, the Turtle was only partially filled with fuel before it was positioned at the head of Australia’s Pearce Aerodrome runway 27 at 7 A.M. on September 29th, 1946.
Lined up for take-off, all fueling was completed by 4:00 p.m. At the same time JATO packs were carefully attached to its fuselage for the jet-assistance required to shove the Truculent Turtle fast enough to take-off before going off the end of the runway
The Turtle would attempt its take-off with CDR Thomas D. Davies, as pilot in command, in the left seat and CDR Eugene P. (Gene) Rankin, the copilot, in the right seat.
In CDR Rankin’s own words :
” Late afternoon on the 29th, the weather in southwestern Australia was beautiful. And at 1800, the two 2,300 hp Wright R-3350 engines were warming up.
We were about to takeoff from 6,000 feet of runway with a gross weight of 85,561 pounds [ the standard P2V was gross weight limited at . . 65,000 pounds. ]
Sitting in the copilot’s seat, I remember thinking about my wife, Virginia, and my three daughters and asking myself, ‘ What am I doing here in this situation ? ‘ I took a deep breath and wished for the best.
At 6:11 p.m., CDR Tom Davies stood hard on the brakes as both throttles were pushed forward to max power. At the far end of the mile-long runway, he could make out the throng of news reporters and photographers.
Scattered across the air base were hundreds of picnickers who came to witness the spectacle of a JATO takeoff. They all stood up when they heard the sound of the engines being advanced to full military power. Davies and Rankin scanned the engine instruments. Normal. Davies raised his feet from the brakes.
On this day, September 29, 1946, the reciprocating engine Turtle was a veritable winged gas tank . . THIRTEEN TONS BEYOND the two-engine Lockheed’s Max Gross Weight Limitations.
The Truculent Turtle rumbled and bounced on tires that had been over-inflated to handle the heavy load. Slowly it began to pick up speed. As each 1,000-foot sign went by, Rankin called out the speed and compared it to predicted figures on a clipboard in his lap.
With the second 1,000-foot sign astern, the Turtle was committed.
Davies could no longer stop on the remaining runway. It was now . . fly or burn.
[ Secretly . . some of the excited end of runway watchers may have wanted to see the airplane crash and burn. ]
When the quivering airspeed needle touched 87 knots, Davies punched a button wired to his yoke, and the four JATO bottles fired from attachment points on the aft fuselage.
The crew’s ears filled with JATO bottles’ ROAR . . bodies FEELING the JATO’s thrust. For a critical twelve seconds, the JATO provided the thrust of a third engine.
At about 4,500 feet down the runway, 115 knots was reached on the airspeed indicator, and Davies pulled the nose wheel off. There were some long seconds while the main landing gear continued to rumble over the last of the runway. Then the rumbling stopped as the main landing gear staggered off the runway and the full load of the aircraft shifted to the wings.
As soon as they were certain that they were airborne, but still only an estimated five feet above the ground, Davies called ‘gear up.’ Rankin moved the wheel-shaped actuator on the pedestal between the pilots to the up position, and the wheels came up. Davies likely tapped the brakes to stop the wheels from spinning, and the wheel-well doors closed just as the JATO bottles burned out. Behind the pilots in the aft fuselage, CDR Walt Reid kept his hand on the dump valve that could quickly lighten their load in an emergency.
Roy Tabeling, at the radio position, kept all his switches off for now to prevent the slightest spark.
The Turtle had an estimated 20 feet of altitude and 130 knots of airspeed when the JATO bottles burned out. The JATO bottles were not just to give the Turtle additional speed on take-off, but were intended to improve the rate of climb immediately after lift-off. The Turtle barely cleared the trees a quarter of a mile from the end of the runway.
The field elevation of Pearce Aerodrome was about 500 feet, and the terrain to the west sloped gradually down to the Indian Ocean about six miles from the field. So, even without climbing, the Turtle was able to gain height above
the trees in the critical minutes after take-off.
Fortunately, the emergency procedures for a failed engine had been well thought out, but were never needed. At their take-off weight, they estimated that they would be able to climb at a maximum of 400 feet per minute. If an engine failed and they put maximum power on the remaining engine, they estimated that they would be forced to descend at 200 feet per minute.
Their planning indicated that if they could achieve 1,000 feet before an engine failure they would have about four minutes in which to dump fuel to lighten the load and still be 200 feet in the air to attempt a landing. With their built-in fuel dump system, they were confident that they were in good shape at any altitude above 1,000 feet because they could dump fuel fast enough to get down to a comfortable single-engine operating weight before losing too much altitude.
Departing the Aerodrome boundary, the Turtle was over the waters of the Indian Ocean.
With agonizing slowness, the altimeter and airspeed readings crept upward. Walt Reid jettisoned the empty JATO bottles. The Turtle was thought to have a 125 KT stall speed with the flaps up at that weight. When they established a sluggish climb rate, Gene Rankin started bringing the flaps up in careful small increments. At 165 KT, with the flaps fully retracted, Tom Davies made his first power reduction to the maximum continuous setting.
The sun was setting and the lights of the city were blinking on as the Turtle circled back over Perth at 3,500 feet and headed out across the 1,800 miles of the central desert of Australia. On this record-breaking night, one record had already been broken. Never before had two engines carried so much weight into the air . . after the JATOS quit.
Their plan was to keep a fairly low 3,500 feet for the first few hundred miles, burning off some fuel, giving them a faster climb to cruise altitude . . and [ hopefully ] costing them less fuel for the total trip.
But the southwest wind, burbling and eddying across the hills northeast of Perth, brought turbulence that shook and rattled the overloaded Turtle, threatening the integrity of the wings themselves.
Tom Davies applied full power and took her up to 6,500 feet where the air was smoother, reluctantly accepting the sacrifice of enough fuel to fly an extra couple of hundred miles if lost, bad WX or other unexpected problems at flight’s end.
Alice Springs at Australia’s center, slid under the Turtle’s long wings at midnight. And Cooktown on the northeast coast at dawn. Then it was out over the Coral Sea where, only a few years before, the LEXINGTON and YORKTOWN had sunk the Japanese ship SHOHO to win the first carrier battle in history, and prevented Australia and New Zealand from being cutoff and then isolated.
At noon on the second day, the Turtle skirted the 10,000 foot peaks of southern New Guinea, and in mid-afternoon detoured around a mass of boiling thunderheads over Bougainville in the Solomons.
As the sun set for the second time since takeoff, the Turtle’s crew headed out across the vast and empty Pacific Ocean and began to establish a flight routine.
They stood two-man four-hour watches, washing, shaving, and changing to clean clothes each morning. And eating regular meals cooked on a hot plate. Every two hours, a fresh pilot would enter the cockpit to relieve whoever had been sitting watch the longest.
The two Wright 3350 engines ran smoothly; all the gauges and needles showed normal. And every hour another 200 or so miles of the Pacific passed astern. The crew’s only worry was Joey the kangaroo, who hunched unhappily in her crate, refusing to eat or drink.
Dawn of the second morning found the Turtle over Maro Reef, halfway between Midway Island and Oahu in the long chain of Hawaiian Islands. The Turtle only had one low-frequency radio, because most of the modern radio equipment had been removed to reduce weight. Radio calls to Midway and Hawaii for weather updates were unsuccessful due to the long distance.
Celestial navigation was showing that the Turtle was drifting southward from their intended great circle route due to increased northerly winds that were adding a headwind factor to their track. Instead of correcting their course by turning more northward, thereby increasing the aircraft’s relative wind, CDR Davies stayed on their current heading accepting the fact that they would reach the west coast of the U.S. [ somewhere ] in northern California rather than near Seattle as they had originally planned.
When Turtle’s wing tip gas tanks empty, they were jettisoned over the ocean. Then the Turtle eased up to 10,000 feet ; later to 12,000 feet.
At noon, CDR Reid came up to the cockpit smiling. “Well,” he reported, “the damned kangaroo has started to eat and drink again. I guess she thinks we’re going to make it.”
The purpose of our mission [ except in Joey’s brain ] was not some foolish stunt, despite her unusual presence aboard.
In the fall of 1946, the increasingly hostile Soviet Union was pushing construction of a submarine force nearly ten times larger than Hitler’s. Antialternative-submarine warfare was the Navy’s responsibility, regardless of the U.S. Army Air Force’s alternative views.
The Turtle was among the first of the P2V Neptune patrol planes designed to counter the sub threat. Tom Davies’ orders derived straight from the offices of Secretary of the Navy, James V. Forrestal, and the Chief of Naval Operations, Fleet Admiral Chester W. Nimitz.
A dramatic demonstration was needed to prove beyond question that the new P2V patrol plane, its production at Lockheed representing a sizeable chunk of the Navy’s skimpy peacetime budget, could do the job. With its efficient design that gave it 4-engine capability on just two engines, the mission would show the Neptune’s ability to cover the transoceanic distances necessary to perform its ASW mission and sea-surveillance functions.
At a time when new roles and missions were being developed to deliver nuclear weapons, it would not hurt a bit to show that the Navy, too, had that significant capabilities.
So far, the flight had gone pretty much according to plan. But now as the second full day in the air began to darken, the Pacific sky, gently clear and blue for so long, turned rough and hostile.
An hour before landfall, great rolling knuckles of cloud punched out from the coastal mountains. The Turtle bounced and vibrated. Ice crusted on the wings. Static blanked out its radio transmissions and radio reception.
The crew strapped down hard, turned up the red instrument lights and took turns trying to tune the radio direction finder to a recognizable station.
It was midnight before Roy Tabeling succeeded in making contact with the ground and requested an instrument clearance eastward from California.
They were 150 miles off the coast when a delightful female voice reached up through the murk from Williams Radio, 70 miles south of Red Bluff, California.
“I’m sorry” the voice said. “I don’t seem to have a flight plan on you. What was your departure point ?”
“Perth, Western Australia.” “No . . I mean where did you take-off from ? ”
“Perth, Western Australia.”
“Navy Zero Eight Two, you are not understanding me. I mean what was your departure airport for this leg of the flight ?”
“Perth, Western Australia. BUT . . that’s halfway around the world ! ”
“No . . Only about a third. May we have that clearance, please ? ”
The Turtle had departed Perth some thirty-nine hours earlier and had been out of radio contact with anyone for the past twenty hours. That contact with Williams Radio called off a world-wide alert for ships and stations between Mid-way and the west coast to attempt contact with the Turtle on all frequencies. With some difficulty due to reception, the Turtle received an instrument clearance to proceed on airways from Oakland to Sacramento and on to Salt Lake City at 13,000 feet.
The weather report was discouraging. It indicated heavy turbulence, thunderstorms, rain and icing conditions.
As Gene Rankin wrote in a magazine article after the flight :”Had the Turtle been on the ground at an airport at that threatening point, the question might have arisen: ‘ Is this trip important enough to continue right through this ‘ stuff ‘?
The Turtle reached the west coast at 9:16 p.m. about thirty miles north of San Francisco. Their estimated time of arrival, further north up the coast, had been 9:00 p.m. They had taken off about forty hours earlier and had covered 9,000 statute miles thus far.
They had broken the distance record by more than a thousand miles, and all of their remaining fuel was in their wing tanks which showed about eight-tenths full. Speculation among the pilots began as to how much further the Turtle could fly before fuel exhaustion.
The static and atmospherics began demonstrating the weird and wonderful phenomenon of St. Elmo’s fire, adding more distractions to the crew’s problems. The two propellers whirled in rings of blue-white light. And violet tongues licked up between the windshields’ laminations. While eerie purple spokes protruded from the Neptune’s nose cone.
All those distracting effects now increased in brilliance with an accompanying rise in static on all radio frequencies before suddenly discharging with a blinding flash and audible thump. Then once again . . slowly re-create itself.
The Turtle’s oxygen system had been removed for the flight, so the pilots were using portable walk-around oxygen bottles to avoid hypoxia at higher altitudes.
The St. Elmo’s fire had been annoying but not dangerous. But it can be a heart-thumping experience for those witnessing it for the first time. The tachometer for the starboard engine had been acting up, but there was no other engine problems. The pilots kept the fuel cross-feed levers, which connected both main tanks to both engines, in the ‘off’ position so each was feeding from the tank in its own wing.
Somewhere over Nevada, the starboard engine began running rough and losing power.
After scanning the gauges, the pilots surmised that the carburetor intake was icing up and choking itself. To correct that, the carburetor air preheating systems on both engines were increased to full heat to clear out any carburetor ice. Very quickly, the warm air solved the problem and the starboard engine ran smoothly again.
With an engine running rough, CDR Davies had to be thinking about their mission. The Turtle had broken the existing record, but was that good enough? It was just a matter of time before the AAF would launch another B-29 to take the record up another notch. The Neptune was now light enough for single engine flight, but how much farther could it go on one engine ? And was it worth risking this expensive aircraft for the sake of improving a long-distance record ?
Over Nevada and Utah, the weather was a serious factor. Freezing rain, snow and ice froze on the wings and fuselage, forcing the crew to increase power to stay airborne. The aircraft picked up a headwind and an estimated 1,000 pounds of ice. It was problematic because the plane’s deicing and anti-icing equipment had been removed as a weight-saving measure.
The next three [3] hours of high power settings and increased fuel usage at a lower altitude of 13,000 feet. And it probably slashed 500 miles from our flight’s record-breaking distance.
After passing Salt Lake City, the weather finally broke with the dawn of the Turtle’s third day in the air. The Turtle was cleared to descend to 9,000 feet. All morning, CDR Davies tracked their progress eastward over Nebraska, Iowa, and the Missouri and Mississippi Rivers. To the north, Chicago’s haze was in sight.
But not surprisingly, our remaining fuel levels were gaining more attention from each and every member of the crew.
The wingtip tanks had long ago been emptied and jettisoned over the Pacific. The bomb bay tank, the nose tank and the huge aft-fuselage tank were empty. Entirely empty. The fuel gauges for both wing tanks were moving inexorably toward zero.
CDR Davies and his crew consulted, tapped each fuel gauges, calculated and recalculated their remaining fuel, and cursed the gauges on which one-eighth of an inch represented 200 gallons.
At noon, they concluded they could not safely stretch the flight all the way to Washington, D.C., and certainly not to the island of Bermuda. CDR Davies chose the Naval Air Station at Columbus, Ohio to be their final destination.
At quarter past one that afternoon the runways and hangars of the Columbus airport were in sight. The Turtle’s crew were cleaned-up and shaven and in uniform. And the fuel gauges all read empty. With the landing checklist completed and wheels and flaps down, CDR Davies cranked the Turtle around in a 45 degree left turn towards final. As the airplane leveled out of its final turn, the starboard engine popped, sputtered and quit . .
The port engine continued smoothly.
Down to 400 feet, as they completed their final turn, both pilots simultaneously recognized the problem. Their hands collided, as both reached for the fuel cross feed fuel lever between their seats.
During the landing pattern’s descending final turn in the landing pattern, the near-empty starboard tank quit feeding fuel into the starboard engine.
Within seconds, the starboard engine began running smoothly again from fuel rushing in from the open cross feed. The Turtle had been in no danger, since they were light enough to operate on one engine. On the other hand, it would have been embarrassing to have an engine quit, in view of the growing crowd watching below.
At 1:28 p.m. on October 1st, the Neptune’s wheels once more touched the earth [ HARD ] with tires intentionally
over-inflated for our take-off at Perth . . 11,236 miles and 55 hours and 17 minutes . . after take-off.
After a hastily called press conference in Columbus, the crew was flown to NAS air station in Washington, D.C. by a Marine Corps Reserve aircraft, where they were met by their wives and the Secretary of the Navy. The crew were grounded by a flight surgeon upon landing in Columbus..
But before the day was over, the Turtle’s crew had been awarded Distinguished Flying Crosses by Navy Secretary Forrestal. Next day, they were scheduled to meet with an exuberant President Harry S. Truman.
And Joey, was observably relieved to be back on solid earth. And she was installed in luxurious quarters at the zoo.
The record established by CDR Tom Davies and the crew of the Truculent Turtle’s crew did not stand for a fluke year or two. But for decades. The long-distance record for all aircraft was only broken by a jet-powered B-52 in 1962.
The Truculent Turtle’s record for piston/propeller driven aircraft was broken by Burt Rutan’s Voyager, a carbon-fiber aircraft, which made its historic around the world non-stop flight in 1986… more than four decades after the Turtle landed in Ohio.
After a well-earned publicity tour, the Truculent Turtle was used by the Naval Air Test Center, at Patuxent River, as a flying test bed for advanced avionics systems. The Truculent Turtle was retired with honors in 1953 and put on display in Norfolk, Virginia, and later repositioned at the main gate of Naval Air Station Norfolk, Virginia, in 1968.
In 1977, the Truculent Turtle was transported to the National Naval Aviation Museum in Pensacola, Florida where it now holds forth in a place of honor in Hangar Bay One.
Many thanks to the Naval Institute Proceedings magazine, Naval Aviation News magazine, the Naval Aviation Museum Foundation magazine, CDR Eugene P. Rankin, CDR Walter S. Reid and CDR Edward P. Stafford, whose articles about the ” Truculent Turtle ” were the basis for this articl
Flight Proficiency 