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extreme P
28th Jun 2006, 21:32
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?

Wino
29th Jun 2006, 06:09
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...

Cheers
Wino

Johnny F@rt Pants
29th Jun 2006, 11:29
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.

UP and Down Operator
29th Jun 2006, 12:09
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" :}

extreme P
29th Jun 2006, 15:59
Our SOP's state max available power before break release in low vis.

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.

411A
29th Jun 2006, 23:22
Standard practise at the airlines were I have worked...low vis defined as 800 metres or less, in many companies.

madtrap
30th Jun 2006, 01:44
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.

747dieseldude
30th Jun 2006, 06:04
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.

Actually, this is the spot where you are most likely to participate in the next accident.
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!

extreme P
30th Jun 2006, 06:19
The question begs asking, how much time does full thrust vs: reduced thrust save you on a take-off roll?

747dieseldude
30th Jun 2006, 06:25
The question begs asking, how much time does full thrust vs: reduced thrust save you on a take-off roll?

It's not just time, it's also distance.

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.

BEagle
30th Jun 2006, 07:52
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.