Hydroplaning on Takeoff example
Showed up at the airport the other day for 0615 L departure. Had already been delayed 24 hours by high winds and heavy snow.
The back side of the low pressure system had been dumping a mixture of rain, freezing rain and freezing drizzle.
The last runway report before we pushed was 90% bare and wet, 10% ice patches. No recent landers.
After type I and IV applications, we were preparing to leave deicing bay when a landed 727 reported "nil" braking (8400 ft runway). I observed where the 727 stopped and would assume that the pucker factor had been high on the rollout. Back to gate we go.
Some seven hours later, the wind is now favouring a different runway (7000 ft), the precip is rain and heavy rain (temp just above 0 deg C) helping to melt existing snow, and now there is a large pool of runway at the intersection of the planned departure runway, about 2000 feet down the take off roll. Various depths are reported: "1/2 inch+ standing water" was the one that got my attention.
We delayed further, but an Emb 145 eventually taxies out, sprays, and then commences the takeoff roll. I watched the takeoff and there was quite a spray back of water during intial roll, then a huge spray when the 145 entered the standing water pool. They continued takeoff without incident.
After a few minutes, one of the pilots radios back that there was hydroplaning on takeoff, and gave the estimated wind report (The airfield indicator had frozen up hours before).
We elected to delay the flight another hour or so and then departed without incident on a different runway. This was day six of a planned four pairing, so we were all motivated to leave.
My question to fellow bigger airplane drivers, have you ever "hydroplaned" on takeoff? Given the crosswind and the standing water, and the NG's fans sitting a few inches above the runway surface I thought it imprudent for us to depart with runway conditions as such. Especially since I had never heard of or experienced hydroplaning on takeoff. Water ingestion into the fans was also in the back of my mind.
I'm not questioning the 145's decision. Different airplane, different load. (We were 143K lbs at takeoff, 10K lbs shy of max takeoff wt.)
Jonny
Last edited by jonny dangerous; 23rd Mar 2008 at 16:29.