If you are late, you're late. Rushing checklists and cutting corners on procedures isn't going to save or make up time. Smooth is fast and fast is smooth.
Yep. So many get into a “mission completion” mindset where the clock becomes the nemesis. Most of the time you get done with your end of things and stare out the window for 17 minutes while the ramp crew loads bags and strollers.
ASAP reports all too often begin with “we were behind schedule...”
LOVED that story Jeremy! So- to us "Peons" please explain why the "weight penalty" with reduced hydraulic capacity? I am not really certain why that is! Thnx, Wade
Wade, having that engine driven hydraulic pump deferred puts us nearer to being on a single hydraulic system, if things go haywire. If the left engine, or the left engine driven hydraulic pump, failed on a flight with the right hydraulic pump deferred, we'd be running our entire hydraulic system on an auxiliary electrical hydraulic pump on the right side, and a transfer pump.
The transfer pump, very similar to the Airbus Power Transfer Unit, is a hydraulically driven hydraulic pump. It uses hydraulic power from the right side to spin up pressure in the left — it doesn't physically pass fluid between the systems, just pressure. So with both engine pumps offline, the entire hydraulic system would be powered by an electrical aux pump - and naturally there is some efficiency lost in that transfer pump. The right system could be at 3,000 PSI on the aux pump, but the transfer pump, especially under load, would pressurize the left system to some values considerably less than 3,000 PSI.
I don't have the stats available, but the best logic I can come up with is that single pump, driving the right system and the transfer pump to power the left system, would retract the landing gear much slower than normal, and the performance hit from that could leave us with a shallower than needed climb after an engine failure on takeoff.
Lowering our takeoff weight by the corresponding penalty (I think it was around 12,000 pounds) would offset the performance hit in such a scenario and still allow us to clear the obstacles in the departure corridor after an engine failure at V1.
The margin for clearing an obstacle on the initial climb after an engine failure at v1 is only 35 feet vertically. Any performance shortfall in that scenario is certainly worth accounting for, which is why we had such a limited takeoff weight.
If you are late, you're late. Rushing checklists and cutting corners on procedures isn't going to save or make up time. Smooth is fast and fast is smooth.
Yep. So many get into a “mission completion” mindset where the clock becomes the nemesis. Most of the time you get done with your end of things and stare out the window for 17 minutes while the ramp crew loads bags and strollers.
ASAP reports all too often begin with “we were behind schedule...”
Absolutely perfect explanation. I really appreciate you sharing and explaining that one. You- obviously- did it properly! Wade
This is great insight into how airlines work for those of us who are used to sitting in the back. Great story!
LOVED that story Jeremy! So- to us "Peons" please explain why the "weight penalty" with reduced hydraulic capacity? I am not really certain why that is! Thnx, Wade
Wade, having that engine driven hydraulic pump deferred puts us nearer to being on a single hydraulic system, if things go haywire. If the left engine, or the left engine driven hydraulic pump, failed on a flight with the right hydraulic pump deferred, we'd be running our entire hydraulic system on an auxiliary electrical hydraulic pump on the right side, and a transfer pump.
The transfer pump, very similar to the Airbus Power Transfer Unit, is a hydraulically driven hydraulic pump. It uses hydraulic power from the right side to spin up pressure in the left — it doesn't physically pass fluid between the systems, just pressure. So with both engine pumps offline, the entire hydraulic system would be powered by an electrical aux pump - and naturally there is some efficiency lost in that transfer pump. The right system could be at 3,000 PSI on the aux pump, but the transfer pump, especially under load, would pressurize the left system to some values considerably less than 3,000 PSI.
I don't have the stats available, but the best logic I can come up with is that single pump, driving the right system and the transfer pump to power the left system, would retract the landing gear much slower than normal, and the performance hit from that could leave us with a shallower than needed climb after an engine failure on takeoff.
Lowering our takeoff weight by the corresponding penalty (I think it was around 12,000 pounds) would offset the performance hit in such a scenario and still allow us to clear the obstacles in the departure corridor after an engine failure at V1.
The margin for clearing an obstacle on the initial climb after an engine failure at v1 is only 35 feet vertically. Any performance shortfall in that scenario is certainly worth accounting for, which is why we had such a limited takeoff weight.
Hopefully that's somewhat clearer than mud.