Reverse during taxi
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Aside from landing, I have, on the A319/320, used only idle reverse during only taxi out at only one airfield, Stuttgart.
It is somewhat downhill to the threshold of 25 and idle reverse helped the brake temperatures to remain below the max brake temperature for take off.
The ops. manual, it has been many years since I retired, at that time, and may still, allowed idle reverse while taxying.
It is somewhat downhill to the threshold of 25 and idle reverse helped the brake temperatures to remain below the max brake temperature for take off.
The ops. manual, it has been many years since I retired, at that time, and may still, allowed idle reverse while taxying.
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The 737 Classic FCTM discusses use of reverse after landing.
Quote: The thrust levers should be positioned to reverse idle by taxi speed then to full down after the engines have decelerated to idle. Unquote.
This suggests that ingestion is not a problem at reverse idle.
Depending on your point of view, it could be argued that providing you don't go above reverse idle (approx. 22% N1) you could slip into reverse idle without harming the engines in order to keep taxi speeds from building up in a long taxi and thus minimising brake heat increase.
Quote: The thrust levers should be positioned to reverse idle by taxi speed then to full down after the engines have decelerated to idle. Unquote.
This suggests that ingestion is not a problem at reverse idle.
Depending on your point of view, it could be argued that providing you don't go above reverse idle (approx. 22% N1) you could slip into reverse idle without harming the engines in order to keep taxi speeds from building up in a long taxi and thus minimising brake heat increase.
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I only ever used reverse (idle) on taxi out on the B737-200 with the clamshell reversers (best reversers I have ever used!), usually only ever in the summer on hot days. As an aside, the 737-family was also the only aircraft type with no brake temp display that I have flown.
At one point on the B737-200 the manuals did permit reversing back from stand, and it was practised in the sim, although never used in reality at BA.
As Finncapt says, taxying out at Stuttgart for Runway 25 was a challenge in summer in the early A320's at BA without the brake fans, although I never had to resort to using reverse, as far as I can recall.
At one point on the B737-200 the manuals did permit reversing back from stand, and it was practised in the sim, although never used in reality at BA.
As Finncapt says, taxying out at Stuttgart for Runway 25 was a challenge in summer in the early A320's at BA without the brake fans, although I never had to resort to using reverse, as far as I can recall.
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Backing off gate using reverse thrust was the normal operation on B727 DC9 MD80 at my US airline in the 80's/ 90's supposedly to save money. They changed back to push back crew with tug in late 90's again to save money .
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Reversing from gate (powerback) is a bit different, because these days there are noise & safety regulations which may limit or prohibit such practice.
Typically at most major airports powerbacks (if allowed) may only be conducted from specific gates during specific times, with prior approval from the airport authority. The airline/operator must also have an approved OpSpec and associated procedures to conduct powerbacks.
Typically at most major airports powerbacks (if allowed) may only be conducted from specific gates during specific times, with prior approval from the airport authority. The airline/operator must also have an approved OpSpec and associated procedures to conduct powerbacks.
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OK, time to inject a bit of logic to this. The aircraft mentioned above that have used reverse in taxi tend to have clamshell reversers and all of the flow is directed by them.
However, aircraft with high bypass engines and sleeved reversers only use the fan air to create a wall of air that causes the drag to slow you. It's less the forward momentum of the air than the large area of disturbed air that acts like a parachute effect.
At idle, the majority of thrust you are getting out the back is the core. SO reverse idle is providing f**t in a spacesuit type usefulness in this case. If you need reverse you need to give it a HANDFUL to do much.
Better to brake to a near standstill and taxi slowly. The friction of braking or riding the brakes is far greater at higher speeds, so controlling the aircraft down a slope is going to generate a lot less heat at walking pace than 25kts.
Also this gives you more time to get to the single engine taxi point and makes for a smoother and quieter taxi in. Just my 20c worth...
However, aircraft with high bypass engines and sleeved reversers only use the fan air to create a wall of air that causes the drag to slow you. It's less the forward momentum of the air than the large area of disturbed air that acts like a parachute effect.
At idle, the majority of thrust you are getting out the back is the core. SO reverse idle is providing f**t in a spacesuit type usefulness in this case. If you need reverse you need to give it a HANDFUL to do much.
Better to brake to a near standstill and taxi slowly. The friction of braking or riding the brakes is far greater at higher speeds, so controlling the aircraft down a slope is going to generate a lot less heat at walking pace than 25kts.
Also this gives you more time to get to the single engine taxi point and makes for a smoother and quieter taxi in. Just my 20c worth...
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Many jets with high bypass engines can powerback, perhaps most notably the 757.
However, most new jets today are not approved for powerbacks -- even if they are physically capable to do so. And as already mentioned, most airports have restrictions against powerbacks.
However, most new jets today are not approved for powerbacks -- even if they are physically capable to do so. And as already mentioned, most airports have restrictions against powerbacks.
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@Amadis of Gaul: checking correct reversers stowage during the exterior pre-flight inspection is a required check for almost any modern jet. You should be able to find it in your FCOM/FCTM.
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There's a requirement by law for the reversers to be visually checked stowed before the take-off. This is usually done during the pre-flight walk-around inspection. Once you used your reversers you must check them visually again, if you are unable to do it from the cockpit/cabin (as the case be with many airliners) you need to stop, shutdown, get out, do a walk around and then continue. Not very practical.
It would be very unpractical as well, any (low speed) RTO would lead to a taxi back to gate for an inspection.
It is irrelevant that we check reversers stowed during the walkaround. IThat still does not make it 'law' to visually inspect reversers after you used them during taxi.
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That's not what I asked. I was inquiring about the "law" that requires shutting down, getting out and checking them again after using them during taxi.
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You don't. It is not required to visually ensure anything. Do you visually ensure your flaps are out on every takeoff? No.
Yes you check the reversers during your walk around. But a walk around is classified as pre-flight. It has nothing to do with the actual operation of the aircraft once moving under power. So no, unless you can quote the article, I'd say there is no general rule or law prohibiting the use of reversers during taxi other than the usual type-dependent operational guidelines which may or may not prohibit their use.
Yes you check the reversers during your walk around. But a walk around is classified as pre-flight. It has nothing to do with the actual operation of the aircraft once moving under power. So no, unless you can quote the article, I'd say there is no general rule or law prohibiting the use of reversers during taxi other than the usual type-dependent operational guidelines which may or may not prohibit their use.
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