Ice is the friend of no plane.
But there was no excuse for the icing problem on the UTAir flight that we are calling the Tyumen crash.
On that flight, both Pratt & Whitney Canada PW124 engines were operating till impact. The plane reached 690 feet and banked 35 degrees to the right, then rolled left banking at 50 degrees, demonstrating instability in the roll axis. Why? Ice.
The ATR 72 had a decent safety record until the 1993 icing incident that caused a fatal crash. This problem was handled by Avions de Transport Regional, the planes designers, by adapting the icing characteristics of the aircraft. They added icing boot extensions to the wing leading edges. (A deicing boot is a ice protection system installed on aircraft surfaces to permit a mechanical deicing in flight.)
The UTAIr 72 was not de-iced at Tyumen before the fatal flight. There’s not much benefit to adding a safety feature if it is ignored.
The ATR 72-210 is equipped with PW 127 engines with a maximum certified takeoff rating of 2750 SHP, and a normal power rating of 2475 SHP. The ATR 72 employs a four bladed propeller. The engine has a reduction gearbox assembly . Because the ATR 72-210 is “stretched” ( much longer than the 42s) ATR 42 pilots are warned about taking off an ATR 72 with too excessive a takeoff pitch angle, which would cause the tail would strike the runway. The ATR 72 has a maximum takeoff weight of 47,465 lbs., and carries 11,020 lbs. of fuel. The engine noise and vibration from the props can get uncomfortable.
Most pilots would not need to be reminded that de-icing is essential when the conditions for ice are likely.
The NTSB has investigated fifty icing accidents and 202 fatalities from 1998 to 2007. We might be able to conjecture that at least some of these incidents would not have happened if the planes had been properly de-iced to begin with, though for some this is too simplistic an assumption.
There were fatal consequences to ATRs which ignored de-icing as demonstrated by the UTair ATR 72 that crashed after taking off from Tyumen in Siberia, killing 31 and mangling 12.
After the disaster, UTAir said that all UTAir planes would henceforth have mandatory de-icing, a change from allowing the pilot to decide whether or not to deice.
Icing has also been determined as the as cause of two earlier fatal ATR 72 crashes:
- -Aerocaribbean Flight 883 crashed near Sancti Spiritus November 2010 killing 68 when the plane encountered extreme meteorological conditions that caused it to ice up at 6,100 meters.
- -American Eagle Flight 4184 crashed killing 68 when in a holding pattern over Chicago encountering a supercooled cloud and rain causing ice which had built up on the wings.
Icing can take place in a temperature band from minus 12 to plus 4 Celsius.
We have seen a dozen ATR 72 accidents caused by other events:
- July 2011-The Eurolot ATR 72 collided with a baggage truck in Warszawa-Frédéric Chopin Airport in Poland.
- Nov 2009-The Kingfisher ATR 72 skidded off the runway on landing at Mumbai-Chhatrapati Shivaji International Airport in India.
- August 2009-The Bangkok Airways ATR 72 that skidded off the runway and struck the Koh Samui Airport ATC tower in Thailand.
- Feb 2008-The Air Bagan ATR 72 that skidded off the runway on takeoff from Putao Airport in Myanmar.
- July 2007-The Jet Airways ATR 72 made a heavy landing before the mid-point of the runway and bounced a couple of times before going off the runway at Indore Airport, India.
- March 2006-The Air Deccan ATR 72 that made a landing at Bangalore Airport that was so hard, the new plane had to be sold as spare parts.
- Aug 2005-The Tuninter ATR 72 ran out of fuel, both engines quit and the plane ditched in the sea killing 16.
- March 2004-The American Eagle ATR 72 that made a bounced landing before skidded off the runway injuring 13 while landing at Luis Munoz International Airport, Puerto Rico.
- Dec 2002-The Transasia Airways cargo flight that crashed into the ocean killing 2 crew.
- Jan 1995-The cargo ATR 72 that crashed in Taiwan killing 4 crew.
- Dec 1994-The Air Gabon ATR 72 skidded off the runway and struck trees while landing at Oyem Airport.