Winter take off question
 

Hello all! I only fly 6 or 7 times a year but experienced an interesting take off last weekend and was wondering if anyone could explain. I was departing Boston Logan during the evening of Saturday December 9th right in the middle of a rather heavy snow storm. I was on an American Airlines Boeing 737-800. After de-icing we reached the end of the runway where the pilot set the brakes and applied power to the engines, maybe 50% with the brakes locked. We stayed in that position for about 20 seconds when he increased to take off power and released the brakes. I was just curious if that is standard for a take off in heavy snow. I have flown in snow before but never had that happen. Thanks in advance for answering my curiosity.

We're going to move this thread to TravelBuzz which is a more apropos forum for travel questions.

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Cholula
CommunityBuzz! Co-Moderator

It is to ensure that the engine anti-ice has cleared the inlets and P2 probes. The higher power setting provides hotter bleed-air for the anti-ice system.

It's to hot up the air going through the bleed system which feeds the anti-ice.

that procedure, among others, came out of recommendations from the NTSB report on Air Florida 90 which crashed on takeoff from Washington National Airport, 13 Jan 1982

Also, with a shorter or contaminated runway, the performance calculations probably called for a standing takeoff where the brakes are held until the engine fan speed is at at a set value (75% N1 for the aircraft I fly). Wing anti ice is normally not turned on after de-icing until just before takeoff as the fluids would be baked onto the heated surface. I would say this was probably a standing takeoff for performance reasons.