Spiral into the Gulf
April 25, 2012 by Bruce LandsbergThere was an unfortunate reminder last week that the high skies, despite a former United Airlines advertising slogan, are not always that friendly. A Cessna 421C on an IFR flight from Louisiana to Florida failed to respond to a Center frequency change and began to circle, inexplicably, as shown in the image. All comments here are purely speculative until the accident report is completed, although my hunch is it will read something like, “Pilot incapacitated, probable cause undetermined.” Recovery of the Golden Eagle is unlikely since it is reportedly in deep water in the Gulf of Mexico.
It is exceedingly rare for pilots to become incapacitated due to an unnoticed pressurization fault. We are trained to go on oxygen immediately before doing anything else and then to start an immediate descent. There are only two GA accidents that I can recall that fit this profile: Golfer Payne Stewart in a Lear 35 (1999) and Bo Rein, the Louisiana State football coach who was lost when a Cessna 441 went off course on autopilot, climbed to more than 41,000 and flew for several hours before spiraling into the Atlantic (1980). Both the Stewart and Rein flight profiles looked similar—aircraft flew in a relatively straight line until fuel exhaustion brought them down. Altitudes were fairly stable.
The flight path in this accident, involving a 65-year-old pilot, looks different with circling and multiple altitude excursions. In all these cases, military aircraft intercepted the target aircraft and noticed there was no response. The cabin windows were fogged over indicating a possible pressurization fault. I asked David Kenny, the Air Safety Institute’s database manager, to do a little research and to speculate with some other AOPA staff pilots on why the flight path looked as it did. You can add your own thoughts:
- The pilot recognized the loss of pressurization in time to disconnect the autopilot, but not in time to actually manage the descent. If he was holding the yoke when he lost consciousness, that might explain the initial right turn which would be consistent with a turn back toward Louisiana. Any deflection of the yoke or asymmetric thrust after he lost consciousness would have been enough to produce circling flight. As long as the airplane was trimmed level or nose up, it would have more or less maintained altitude or gradually climbed until it stalled.
- The autopilot was set to wing-leveller mode without altitude hold.
- The autopilot was tracking away from a VOR and reverted to wing-leveller mode once VOR reception was lost. This is consistent with the track, which was following a radial from the Leesville (LEV) VOR when the wandering began. The flight plan had been filed as “/G,” but we don’t know whether he was navigating by VOR or GPS at the time. Again, we’d have to assume that it wasn’t set for altitude hold.
Another mystery involves the reportedly “gentle” splashdown after the aircraft ran out of fuel.
The FAA sums up the best practices in the advisory circular AC 61-107A OPERATIONS OF AIRCRAFT AT ALTITUDES ABOVE 25,000 FEET MSL AND/OR MACH NUMBERS (MMO) GREATER THAN .75. It’s a good review.
Here are a few reminders:
The time of useful consciousness at FL270, the flight’s filed altitude, is about three minutes if the cabin suffers a slow decompression and about half that with a rapid decompression. There is an annunciator light to warn the pilot, and there are some physiological signs such as euphoria, sweating, headache, fatigue, tunnel vision, hot flashes, etc. The lack of oxygen affects all of us a bit differently.
When in doubt, quickly don the mask (cannulas are OK below 18,000; you did remember to check mask/cannula before takeoff and that there is adequate supply?) and then figure out what happened. Those of us who don’t fly the flight levels still need O2 for prolonged flight above 10,000 (5,000 at night), although using it at lower altitudes couldn’t hurt, and may in fact be necessary if lack of sleep, age, smoking, and other habits are causing a hypoxic condition before ever leaving the ground. It’s better for your brain and your alertness level. There are a number of mishaps where a perfectly capable pilot does something unexplainable where oxygen deprivation seems as likely as many other answers, and it’s easy to remedy!
Our condolences to the family and friends of this C421 pilot—unexplained accidents are always unsettling.
Bruce Landsberg
President, AOPA Foundation
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Bruce Landsberg, President of the AOPA Foundation
April 27th, 2012 at 3:43 am
I went through the US Navy’s hyperbaric chamber in Pensacola, FL. Hypoxia sneaks up on you very quickly. Once you pass out, it’s over. It’s been described as the nicest form of execution. Most civilian pilots never experience actual training in the chamber so an accident is likely possible snd the iced/fogged windows support a depressurization problem.
Thinking out of the box, on several occasions pilots have attempted suicide (C-210 off Jacksonville in the 1980s, USAF A-10 into a mountain). This doctor recently had some of his plastic surgery certs revoked and faced law suits. While I seriously doubt if suicide was his intention, it remains a possibility. No one knows for sure what goes on with private lives so this will likely remain an unsolvable mystery.
April 27th, 2012 at 6:36 am
Patrick…
Thanks for your note. Human factors and the pilot’s mindset is something that certainly comes into play although it is frequently not factored into accident investigations.
April 27th, 2012 at 6:52 am
Would the fuel burn have affected the spiral? If the tank was set to the Left tank, as it burned the weight would have been to the right, which I think would have changed the w & b. Thoughts?
April 27th, 2012 at 7:08 am
The moving spiral is what you’d expect for an autopilot circle affected by a prevailing, but slightly inconstant wind from about 270. The hiccup near the middle could have been caused by a one-time gust, stretching out that part of the turn.
April 27th, 2012 at 7:10 am
This is a reminder to ALWAYS DO THE PRE FLIGHT CHECKLIST. As owner of many high flying Cessna’s over the years, I know the Cessna Presurrization systems are essentialy indentical from model to model to the 421. Preflight, preflight, preflight and do not succumb to the temptation to fly with a less than FULL O2 bottle.
April 27th, 2012 at 8:09 am
I have flown C-421c’s for more than ten years and can suggest the following scenario:
1- Pilot had possible low pulse-ox to start with
2- Cabin was not at proper pressurization setting or failure of system (very very rare)
3- Pilot did not or could no follow POH emergency procedure for loss of cabin pressurization
4- And here is the critical possibility: The aircraft had a Cessna ARC IFCS or autopilot
5- Pilot when incapacitated hit or moved the turn knob on the ARC autopilot control just enough to be out of the detent and start slow (13 minute~ per turn) turns
The bigger question is his flight planned altitude. While the C421c has a very high service ceiling it is not common at all to use these FL’s unless you have a very good reason. This was a short trip 600 mile or less and the time, fuel and stresses on the aircraft do not justify these altitudes.
my $.02
April 27th, 2012 at 9:20 am
I was wondering why, with over 3 hours to plan a rescue, all that could be done was watch the aircraft splashdown and sink? Is that much time at that altitude not survivable?
April 27th, 2012 at 9:38 am
Last question first–absolutely not survivable. The pilot had undoubtedly died literally hours before splashdown.
As a USAF ROTC cadet, I had a “ride” in the USAF’s altitude chamber at Buckley AFB in 1965, and it was an eye-opener. I’d lived at high altitudes most of my life (Laramie-7300′ MSL) and thought I was immune to high altitude issues. Not so–I was as much a victim as any of my compatriots, becoming essentially incapacitated within 3-4 minutes at 27,000′ (my recollection of exact altitude is foggy–it might have been lower).
Over the last few years, I’ve learned to use my pulse-ox meter in the cabin, to determine when I need to go on oxygen–and that’s in my hotrod 172 that tops out around 15,000′ density altitude. I now routinely use the bottle over 10,000′ DA, sometimes lower. Age probably makes some of the difference, because otherwise I’m in good health.
There are many factors that go into how high one can fly w/o oxygen and still function well, and the FAA’s requirements are too high for many to function well.
Regardless of the details, it’s apparent that this particular pilot succumbed to lack of oxygen, a lesson for all of us that we really do need air, no matter how sophisticated or unsophisticated our airplanes may be.
April 27th, 2012 at 10:11 am
A couple more theories. The first, rather conspiratorial, but what the heck…we’re all speculating…right?
Remember a few years ago, someone faking their own death by parachuting out of their own airplane (I believe this was in Alabama) ? What were the financials of this doctor? Was he being sued/divorced, etc.? Could climbing out on a wing with a parachute (even if the door could be opened and slammed at that speed), disturb the autopilot sufficiently to cause a low-banked, consistent turn? Were divers sent to confirm the existence of an occupant of the aircraft at 1,500 below sea level?
Back to reality:
Pilots that fly at that altitude are trained the first order of business during a pressurization failure is to don an oxygen mask, fly lower, troubleshoot the situation and communicate their situation / intentions. Assume a failure in the oxygen system (partial blockage, broken valve, depleted supply, kinked or broken line, improper installation, etc.). The pilot might not have been incapacitated at all: Could he, under the effects of hypoxia (not complete incapacitation), have assumed that the fogged / iced windows were presenting an IMC condition, and assumed he was flying straight-and-level through a cloud layer? Could he have partially regained his consciousness, confused about the low fuel situation, and performed adequate ditching procedures, only to be knocked unconsious permanently by the impact?
I realize these are more questions than answers…but they probably should be asked. Along with, if it was perceived that the aircraft made a soft “landing,” why could the observer of that landing not reach the aircraft in time to perform a rescue / retrieval?
April 27th, 2012 at 11:47 am
I’ve had 2 pressurization failures in over 14,000 hours of flying pressurized aircraft. One was a door seal failure on a Cessna Citation at FL 370. After an hour of cruise, the cabin started climbing gradually. The cabin advisory horn came on, and the masks dropped. We went on oxygen and declared an emergency. The cabin never went above 16,000 feet–even with the power levers pulled back. Leaving the power levers UP, the cabin maintained a 4.5 differential–under 8000′ at FL 200. We finished the trip at that altitude.
The second was an explosive decompression at FL 270 in the climb in a Sabre 60–caused by a rupture of the main pressurization duct. We went on oxygen, declared an emergency, selected emergency pressurization (no help) and descended to 10,000′.
Some of the items that many instructors at training schools (and magazine writers) fail to mention are:
The difficulty of donning a mask over headsets. For that reason, I don’t use headsets in pressurized aircraft any more–note that the airlines rarely do, either.
The NOISE associated with an explosive decompression–and on many aircraft, the noise from the emergency pressurization. In the Sabreliner, it takes straight bleed air from the engine.
The difficulty in communicating with ATC OR your other crewmembers because of the noise. In our case–we couldn’t hear ATC–we transmitted our emergency in the blind. It resulted in a loss of separation–we were 3 miles behind a LearJet in the descent. We had to yell to communicate with the first officer.
The need to switch to the oxygen microphone. For sanitary reasons, most simulators “simulate” putting the mask on in the simulator–and with 5 type ratings, not one actually had us switch over the mike.
The quality of the microphone in the oxygen mask is often poor. ATC had a hard time understanding our transmissions.
We filled out the NASA forms after landing–the FAA did follow up, but complimented us on our handling of the emergency–as did the NASA reporter.
April 27th, 2012 at 11:59 am
Let’s put Scott’s theories to rest quick. At flying speed it is very doubtful the pilot could open the door, period. I think we would all like to believe that he ejected and is living happily in Brazil with his soul mate. However, the truth is that he was probably dead within an hour of the lost comm. Those of us who have done high-altitude chamber work in any of the armed services know that it sneaks up on you in a flash and its over quick. Remember trying to play patty cake with the person next to you? We exploded in fits of giggles trying to hit each others’ hands.
To me this is a simple case of O2 depravation.
April 27th, 2012 at 12:43 pm
I went through the Chamber back in the day and again a few times since. As they told me, my initial symptoms (unique to each individual and probably constant throughout your life) were an extreme feeling of heat. Knowing this, I feel prepared for any loss of pressurization. If you ever have the cahnce to take a Chamber ride, it is well worth while.
April 29th, 2012 at 7:02 pm
The 421C I flew for 600 hours had a 28 gal aux tank in the left nacelle. I would start the transfer pump 30-60 minutes after take off, and it took about 90 mins to make the transfer. I would start a cross feed, left to right, at the beginning of the final 30 mins of transfer. At the 90 minute point I would turn off the transfer pump, return the cross feed to mains and the fuel would be balanced. If the Dr from Slidell had a carbon monoxide leak he might have already started the transfer before he passed out from CO poisoning. Of course, he would not have done the cross feed portion of the balancing procedure and the plane would begin to spiral due to the fuel imbalance or the right hand end would exhaust it’s fuel supply about 70-80 mins before the left side. Few, if any, autopilots could keep the wings level with neutral trim and either scenario.