Colgan 3407

48 Seconds. A span of time this short could easily get lost in the minutes and hours of a normal flight. Enough time to complete about half of a landing checklist, fly 3/4 of a leg in a hold, or on occasion for a flight to proceed from normal to unrecoverable. In the latter situation, what would normally be otherwise insignificant moments in time become turning points where decisions made define the outcome of a flight, good or bad. Such was the case with Colgan Flight 3407.

At 22:16 and 4 seconds, the crew of Colgan Flight 3407 were turning to intercept the localizer for the ILS approach into Buffalo, while at the same time lowering the landing gear. The flight up to this point was proceeding, in most respects, quite normally. At 22:16 and 52 seconds the end of the CVR recording is marked by a scream from First Officer Rebecca Shaw immediately prior to the flights impact with a house underlying the approach path. These 48 seconds have been highly scrutinised since the recovery of the CVR and FDR from the wreckage of 3407, and will likely continue to be. While 22:16:04 marks the point at which the sequence of events began to deviate from what would be a normal flight, it was during the previous 30 minutes which preceded those fateful 48 seconds that the stage was set for the accident that would follow.

At 21:52:57 the crew picked up the ATIS for Buffalo which called the visibility at 3 miles in snow and mist, with the winds 250 degrees 15 knots gusting to 23. At 21:57:10 the flight is cleared to descend to 11'000. At the turn of the hour, the conversation in the cockpit turns to the crews' experiences with controllers and the past flying experiences of the Shaw while she was based out of the midwest. Neither crew member calls leaving their cruising altitude of 16'000, although at 22:03:41 a sound similar to the altitude alerter is picked up by the cockpit area microphone which could indicate that the aircraft was approaching their cleared altitude of 11'000.

At 22:04:12 Captain Marvin Renslow spends 38 seconds on a partial approach brief for the ILS to Runway 23 into Buffalo. Shortly afterward the flight is cleared to descend to 6000 by Buffalo Approach while the crew discusses an operating procedure used in the flying the Saab, one of the other aircraft types operated by Colgan. At 22:05:29 Captain Renslow finishes the approach brief started a minute earlier. At 22:08:41 the flight is cleared down to 5000, followed by a clearance down to 4000 36 seconds later at 22:09:15. Upon being cleared to 4000, the captain questions the first officer about how her ears were doing to which she replied they were "stuffy".

At 22:09:35 the crew makes mention of ice build-up which is starting to show on the windshield. With this discovery of the ice accumulation the first officer makes mention of her lack of exposure to icing conditions while flying out of Phoenix and that she is grateful for a winters worth of experience as a first officer prior to getting upgraded to captain on the Saab. At 22:12:17 the flight is cleared down to 2300, and shortly afterward is given a heading of 330 Degrees to fly for vectors for the ILS Runway 23. At 22:13:24 the Captain calls for the descent checklist, approximately 10 minutes after the crew had commenced the descent. 10 Seconds later the captain also calls for the approach checklist. In the period immediately before and after the descent and approach checklists are called for and for most of the remainder of the flight, the conversation is centered around the first officers inexperience with flight in icing conditions. At 22:15:06 the Captain calls for and the First Officer sets flaps 5. The flight is then given a heading of 260 degrees by Buffalo Approach to intercept the localizer for the ILS Runway 23. At 22:15:59 the cockpit microphone picked up a sound similar to a decrease in engine power and 17 seconds later the captain called the localizer alive and for gear down. At 22:16:14 the first officer confirmed the landing gear was down, after which the captain called for flaps 15 to be set and the landing checks. At 22:16:27 the sound of the stick shaker, which warns of an impending stall, activates.

Look at the Flight Data recorder information for the same period of time, and it becomes quickly clear what was happening behind the scenes that the CVR only hints to. At 22:16:00 Captain Renslow reduces the power to flight idle to slow for the approach. He then calls "gear down, loc's alive", and in response to this First Officer Shaw lowers the landing gear and moves the condition levers to their maximum position which gave a prop rpm of 1020. The action of both extending the gear and bringing the condition levers forward, while being a normal procedure, introduces a considerable amount of drag from the gear entering the airflow and the props moving to a fine pitch. These two actions, coupled with the engines being at flight idle, allowed the airspeed to decrease from 170 to 149 knots over the course of the next 10 seconds.
When Captain Renslow calls for "Flaps 15, before landing checklist." First Officer Shaw pauses for a few seconds, and when she does move the flap handle, positions it at Flaps 10 instead of the called for Flaps 15. Immediately after selecting Flaps 10, First Officer Shaw utters "uhhhh"
which may have been in response to the decaying airspeed which was decreasing through 130 knots at that point. At 22:16:27, the moment at which the stick shaker activated, the airspeed was at 126 knots and the flaps were moving through 6.7 degrees. The activation of the stick shaker disconnected the autopilot, which had been on up until that point in the approach.

The cockpit would have not been a place of calm and quiet at this stage in the flight. The stick shaker would have been aggressively shaking the controls to warn of an impending stall, while the autopilot disconnect horn blared in the background. Amid the chaos of the cockpit warnings, the crew exchanged no words, no acknowledgement of the stick shaker or the autopilot disconnect, nothing but silence for the next 10 seconds.

In response to the activation of the stick shaker, Captain Renslow almost immediately applies nearly 30 lbs of back pressure to the controls and brings the power levers forward to about 80% power. The action of applying back pressure on the controls resulted in the aircraft pitching up to around 30 degrees nose up, and with the applied increase in power the aircraft began to turn left, a normal tendency of prop driven aircraft. By the top of its short lived climb which peaked at 2600, the aircraft was banked 45 degrees to the left.
Shortly there afterward, the stick pusher, which is a last defense safety mechanism designed to help prevent a stall, begins to apply forward pressure to the controls. The Captain counters this with a 40 pound application of back pressure. At this point in time the airspeed is fluctuating around 100 knots and the angle of attack 23 degrees. The aircraft then begins to simultaneously pitch down and roll rapidly to the right, rolling from a left bank through wings level to a 110 degree bank to the right in the matter of seconds. "Jesus Christ" is all Captain Renslow responds with. As the aircraft was rolling right, First Officer Shaw, without being prompted to do so, selects Flaps Up, which she announces to Renslow shortly afterward.

Using full left rudder and aileron deflection, Renslow is able to roll the aircraft back to near wings level. For a moment the stick pusher stops and as it does the backpressure increases to 60 lbs. The Stick pusher activates once again, and again the Captain overrides it for the remaining 12 seconds of the flight with backpressure ranging from 80 to 120 lbs of force. As a result of these control inputs, the aircraft rolls rapidly again to around 90 angle of bank to the right and the nose falls to 45 degrees nose down.

First Officer Shaw asks "Should the gear up?"
"Gear up, ..ohh #" Responds Captain Renslow

While the crew did manage to get the angle of bank to around 30 degrees and the nose up to -25 degrees, the aircraft had developed a 10'000 foot per minute rate of descent from which there was little, if any, possibility of recovering. The scream emitted by Shaw at 22:16:52 makes it chillingly clear what would occur next.