AOPA ASI Blog: Leading Edge

This is a reminder regarding ice – seems appropriate for the season.  Below is an edited NTSB Preliminary report on a fatal TBM 700 accident that happened just before Christmas:

On December 20, 2011, about 1005 eastern standard time, a Socata TBM 700, collided with terrain following an in-flight loss of aircraft control near Morristown, New Jersey. Visual meteorological conditions prevailed and an instrument flight rules flight plan was filed for the flight from Teterboro, New Jersey (TEB) to Atlanta, Georgia (PDK).  The flight originated from TEB at 0950.

A preliminary review of recorded radar and voice communications revealed that the pilot was in communication with the Federal Aviation Administration, New York Air Route Traffic Control Center (ARTCC). While flying at 17,000 feet mean sea level (MSL) the pilot reported that he was in icing conditions. The pilot requested a climb, and the flight was subsequently cleared to flight level (FL) 200. The aircraft reached a maximum altitude of 17,900 feet and then began to descend. Radar and radio contact with N731CA was lost about 1005.

A post-crash fire was evident in the highway median, where the fuselage came to rest. The outboard section of the right wing and several sections of the empennage were found about 0.25 miles southwest of the fuselage, in a residential area.

The pilot held a private pilot certificate with ratings for airplane single-engine land and instrument airplane. He reported a total flight experience of 1,400 hours on his latest second-class medical certificate application, dated July 14, 2011.

This is an unusual accident  in that it involves an “icing-approved” turboprop. These aircraft spend a lot of time passing through icing conditions and they are rigorously tested to handle moderate conditions. Remember that severe conditions, by definition mean that the systems are not able to keep up. At this point we just don’t know.

While we are, as usual, very early in the investigative process there is circumstantial evidence that ice may have brought this aircraft and an entire family to grief. Without speculating further we offer a few reminders:

1. Ice is where you find it – not where it is forecast (more to say about forecasting in a future blog). At this point we’re not sure what the forecasts were.
2. Even approved aircraft should be working to get out of it and should not hesitate to advise ATC that they need different altitude. If it’s bad – by all means, declare an emergency! Aircraft of this type spend considerable time in the icing environment but not necessarily in these exact conditions. More to come.
3. Be sure all anti and deicing equipment is operative before takeoff and use it appropriately. Iced up engines and exterior surfaces will not support flight. It may not be possible to determine this from the wreckage so no judgments are offered here.
4. Turn off the autopilot as soon as icing is encountered – it tends to mask aerodynamic effects and then when it can’t fly any more hands the mess back to the pilot – usually badly out of trim!

Again, we may not know how the automation was used. It will likely come out in the investigation, but it appears that an in-flight breakup occurred which is why the wreckage was scattered. Once the airspeed exceeds Vne there are no guarantees that the airframe will hold together and unusual attitude recovery under these circumstances is not something that most of us have experience in.

I once practiced a Vne spiral in one of FlightSafety’s twin simulators, while attempting to recreate another loss of control accident from the flight levels. Two things stood out – the speed builds really quickly and to successfully recover from the dive without overloading the airframe, one needs to push on the controls as the aircraft is brought to wings level flight. This is because the aircraft will seek trim airspeed which is likely much slower than the speed in a dive.

We had no way to simulate the effects of ice-degraded airfoils so the results were speculative. Simulators also do not disintegrate as an aircraft might. As a quick refresher,  here is a link to ASI’s Aircraft Icing Safety Advisor.

Pireps can make a huge difference and if you get into ice and particularly serious icing – file an urgent pirep with ATC or Flight Service.

This was a very sad way to wind up 2011 and let’s resolve to finish up icing season without any more mishaps. Accidents like this reflect throughout the community. Our thoughts are with the families and friends.

For more information on Cold Weather Operations please visit ASI’s Cold Weather Resources Safety Spotlight.