6 November 2006
An interim report on the <a href=”http://ntsb.gov/Pressrel/2006/061103.htm”>on-going investigation by the NTSB<a> (US National Transportation Safety Board) into Cory Lidle’s crash <a href=’newsfeed.php?artnum=311′ target=’_blank’>last month</a> has hinted that the crash may have been due to neither pilot appreciating the tightness of the turning circle required to negotiated a U-turn on the East River.
The way that the NTSB is thinking is this: the wind at the time of the accident, reported on the ground as 6 kt at 060 degrees, was reported at the same by an aircraft landing at nearby Newark as 13 kt from 095 degrees. The speculation is that the Lidle aircraft turned with the wind at its tail; the wind therefore pushed it further towards the buildings than intending. In addition, the pilots started the turn closer to the middle of the river than was necessary. Both factors combined cut the turning space available from a potential 2,100 ft to just 1,300 ft, according to the NTSB.
Calculations show that this turn would have required a constant 53 degrees of bank in the turn – but, of course, if the turn were started at too slow a rate, an increasingly high bank angle (an increasingly dangerous manoeuvre) would have been required. Nothing wrong with a high bank angle turn – you’re prepared for it and if you’re at a decent height. Lidle and Stanger were following the corridor which allowed them to fly not above 1,100 ft.
The turn was almost certainly initiated because La Guardia airspace was ahead of them. Since the accident, aircraft have banned from flying the corridors over the rivers on either side of Manhattan (which Lidle and Stanger were flying) without being in contact with ATC (although there are exceptions); one of the effects of this is that ATC can now instruct pilots to turn with plenty of room.
The investigation has shown no irregularities with the flight, pilots, aircraft or engine.
The NTSB report has so far not come up with a definitive cause for the accident.
