Airbus Reversers and landing distance

[Pilotas]

hello.
as we can see here on the actual landing distance table there are zeros in "2 rev op" graph for dry and wet runways. does it mean that use of reversers gives no reduction in landing distance?
http://se.uploads.ru/d/6AGes.png

[AerocatS2A]

It means you don't get to count the benefit from reverse thrust. The reverse thrust might reduce the distance by 5%, but for regulatory reasons you are not permitted to factor this in to your landing performance tables under dry or wet conditions.

[A Squared]

Well, I don't know, I'm just speculating, so take this for what it's worth. I'd *speculate* that this is some sort of regulatory thing, rather than a real physical effect. Obviously, you'd expect landing roll with reverse to be shorter than landing distance without reverse, all else being equal (surface condition, braking effort, etc) . It wasn't that long ago when all published landing distances were predicated on brakes only, no reverse. Sometime in the last couple of decades regulatory agencies began allowing the use of reverse to be included in operational landing distance data. Not having flown an airplane for which this is true, I don't know the details of how this is accomplished or what regulatory limitations are in place. So, my speculation is that this is the result of some regulation that your charts for dry and wet runway don't show a shorter landing distance with reverse.

Hm, looks like Aerocat beat me to this.

[Chesty Morgan]

Landing distance with autobrake is generally the same (there are slight variables) with or without reverse as the brakes modulate to give a fixed deceleration rate. With reverse there will obviously be less retardation effort from the wheel brakes.

[FullWings]

As Chesty says, it’s down to the autobrakes. If the deceleration required is less than that available from wheel braking alone, then reverse has no effect on the stopping distance. It’s only when runway friction goes below a certain level that reverse comes into play in actually reducing the achieved distance.

I suspect you will see a significant difference if you look at the poor/slippery tables...

[vilas]

If there was no benefit then obviously no one will fit and maintain reversers it costs money. Which aircraft chart is this? A320 chart shows credit for reversers even on dry runway. It increases as braking efficiency degrades.
Regulations say:
Braking Means other than wheel brakes: Spoilers, reversers (except on dry runway), can be used when they are safe and reliable.

[PEI_3721]

An overview of Airbus landing distance and corrections based on OLD/FOLD data is in http://www.airbus.com/company/aircraft-manufacture/quality-and-safety-first/library/?eID=maglisting_push&tx_maglisting_pi1%5BdocID%5D=231880 Page 5

See the example chart on page 7 which shows 'rev' corrections for all braking categories.

I assume that the OP chart is out of date as it is titled "Actual Landing Distance", whereas more recent data (OLD/FOLD) is titled 'Required Landing Distances'. However because I do not have an actual aircraft reference to check please refer to a real aircraft document.

Airbus 'Safety First' Library | Airbus, Commercial Aircraft (http://www.airbus.com/company/aircraft-manufacture/quality-and-safety-first/library/)
There is an index of articles for each issue.

[Pilotas]

Which aircraft chart is this?

it is A320

[vilas]

Pilotas
Your document is obsolete. The current document shows credit for reversers.

[EGPFlyer]

As Chesty says, it’s down to the autobrakes. If the deceleration required is less than that available from wheel braking alone, then reverse has no effect on the stopping distance. It’s only when runway friction goes below a certain level that reverse comes into play in actually reducing the achieved distance.

I suspect you will see a significant difference if you look at the poor/slippery tables...

Almost.. you'll get a small decrease in landing distance as the reversers kick in before the auto brake.

[Jonty]

Pilotas
Your document is obsolete. The current document shows credit for reversers.

These are auto brake distances. No credit for reverse as all that will happen is the brakes release. Useful for keeping brake temps down though.

[Flightlevel380]

No credit for reverse


hello.
as we can see here on the actual landing distance table there are zeros in "2 rev op" graph for dry and wet runways. does it mean that use of reversers gives no reduction in landing distance?
http://se.uploads.ru/d/6AGes.png

[vilas]

I am not able to attach the reference QRH but it is 1.8 STD. It has credit for reversers except for DRY runway medium brakes. Even for dry runway for manual braking and low auto brake it is -10mtr/per reverser.

[aloa326]

Not forgetting to mention that reverse has to be Full.
Idle reverse no credits.

[AerocatS2A]

Just out of curiosity, I presume there are charts for manual braking, do they give a credit for reverse in dry and/or wet conditions?

[CaptainMongo]

I am not able to attach the reference QRH but it is 1.8 STD. It has credit for reversers except for DRY runway medium brakes. Even for dry runway for manual braking and low auto brake it is -10mtr/per reverser.


Our company manual performance tables indicated as you described, no reverser credit for dry runway, medium brakes.