Full Thrust Required below 1400 RVR
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Full Thrust Required below 1400 RVR
Strange requirement that nobody seems to now the origin of. It pertains to Canadian 757 operations and is not in the CARs. Anyone with any insight into the practice?
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I always go max for a low vis takeoff. To many things can wander across the runway in the fog unknowingly, so I minimize my time on the runway. There have been a number of near misses avoided as a result of that...
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Full thrust take off in low vis
Personally I prefer to use the max permitted reduced thrust. In the event of an engine failure at V1, there's less yaw and a better chance that I'll keep it going in a reasonably straight line. It seems to have worked ok in the sim so far, I hope that I never have to try it out for real.
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Our SOP's state max available power before break release in low vis.
Theory here is as well, that shorter time on rwy will minimise risk of running into something crossing the rwy in the fog, plus that you really just want to get away from the ground and all obstacles when you are IMC.
"climb higher, we can almost make it"
Theory here is as well, that shorter time on rwy will minimise risk of running into something crossing the rwy in the fog, plus that you really just want to get away from the ground and all obstacles when you are IMC.
"climb higher, we can almost make it"
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Our SOP's state max available power before break release in low vis.
Given ground radar, airport lighting and restrictions on movement under CAT II/III operations I think the potential for a collision with either another airplane or vehicle is slim.
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I reckon the difference in time on the runway between a reduced thrust setting and full poke isn't all that significant. One might also argue that by accelerating more quickly, that you might smack something before it has a chance to clear the runway 
I agree with Johnny, but would also like to suggest that engine failures are more likely when the engine is working harder. Has everybody seen the pix of the uncontained CF6-80A failure on an AA 767 at LAX on June 2nd? That was a high power run-up.
There is no rule or guidance in Canada that advocates such a thing. Air Canada used to do so, but changed after the CAIL merger when the logic was revisited.
I agree with Johnny, but would also like to suggest that engine failures are more likely when the engine is working harder. Has everybody seen the pix of the uncontained CF6-80A failure on an AA 767 at LAX on June 2nd? That was a high power run-up.
There is no rule or guidance in Canada that advocates such a thing. Air Canada used to do so, but changed after the CAIL merger when the logic was revisited.
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Originally Posted by extreme P
What do your SOP's define as low vis?
Given ground radar, airport lighting and restrictions on movement under CAT II/III operations I think the potential for a collision with either another airplane or vehicle is slim.
Given ground radar, airport lighting and restrictions on movement under CAT II/III operations I think the potential for a collision with either another airplane or vehicle is slim.
Runway Incursions are defined as one of the major risk factors in aviation.
For one, ground radar does not protect against runway incursions, even systems like SMGCS-1 & 2 (2 is not operational yet) only provide protection against ~50% of RI situations.
Airport lighting? Do you know how many airport markings and lightings do not conform with ICAO standards? Are you aware of how little pilots and vehicle drivers know of their meaning and of the Low-Vis procedures?
I would minimize the time spent on the runway, and get the hell out of there!
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Originally Posted by extreme P
The question begs asking, how much time does full thrust vs: reduced thrust save you on a take-off roll?
Just a frew months ago, a big accident was avoided in JFK by using max takeoff thrust:
And ISR 767 blundered onto the runway by mistake, during low-viz with heavy rain.
An ABX DC8 who was rolling down the runway, caught sight of the 767 in it's path and managed to takeoff before it, passing just a few feet above.
The DC8 was using max takeoff thrust, because of the rain. Had it been a normal, reduced power takeoff... just imagine.
In the type I flew (4 x rear mounted low ratio bypass engines), I used to recommend full power if there was a strong crosswind to accelerate more quickly to a speed where control effectiveness was better.
No risk of surge on that type. But it was certainly a bit of a handful in strong crosswinds.
No risk of surge on that type. But it was certainly a bit of a handful in strong crosswinds.
