When I started flying for the airlines a long time ago it the definition was pretty vague and e.g.
light or medium reverse was standard.
The effectiveness depends on the design as well and on most present hi bypass engines only the fan air is being redirected which means at max reverse the core engine delivers full forward thrust.
On the A320 max reverse thrust on a dry runway shortens the landing distance by less than 50m.
Yes but, as you know but for the audience: On a contaminated runway reverse makes a world of difference.
A world of difference is a little bit exaggerated IMO.
Even on a contaminated runway the landing distance reduction is just a tad more than 100m.
Contaminated with what, I guess is the question then? On ice at 60,000 kg I read 2,900 meters versus 2,175 meters actual, on a 2,500 meter runway I suspect that would affect the amount of post-landing paper work quite a bit… Bet you looked at 1/4" water : ) So yeah it would depend on circumstances.
No. Wet, water and snow.
Confirm you are using the unfactored distance and not the required landing distance?
Not sure which SOPs or airline would allow a landing on an ice covered runway…
That’s interesting. I’ve been on thousands of flights in the US and international and I can’t recall one flight that didn’t use reverse thrusters. Even props use it.
Havent flown to Canada i guess?
A320 ops with reported BA poor?
Do you know which airline operates that way?
Reverse thrust in conjunction with autobrake does not in itself reduce landing distance, it is used to keep the brake temperatures lower for quicker turn around at the gate and less brake wear for economics. Autobrake enforces a specific deceleration rate, the same rate using reverse thrust or not.
maybe not a320, but old 737-200 surely go on Ice, or with poor braking action runways, because a lot of canadian airlines have them (could check Air Inuit/Nolinor/etc)
We send our Challengers to 100% ice runways too
OFC there must be 0 xwind, and its not gonna be 5000’ long runways
If reverse thrust shortens the landing distance, it’s IMO obvious that it involves full manual braking without autobrakes.
Yeah, unfactored, used this table from an almost 20 year old A319 manual. Maybe the data or formatting looks different these days but it is what I have available…
I have no experience with the A320, but I fly the 747NG/MAX IRL and we always use at least “Detent” Reverse (first notch). Very few places were we do not use any reverse, but even those (due to noise) we use idle reverse. Relying on the Brakes alone is hard on the aircraft and also causes high brake temperatures. Additionally, if you are landing on snow or rain covered runways, relying on the brakes alone to slow is not a good idea due to reduced traction. The spoilers are required to be armed for every landing (with very rare training exceptions - ie touch and goes). Personally I use detent reverse even if noise requirements dictate idle in most cases except when I go to Europe. Flight safety trumps someone’s sensitive ears. In 12 years of flying the 737, I have never once heard been in trouble for a noise violation. They just plain don’t track them (in North America at least). Gatwick I know has microphones and does track it so I use Idle there.
On those tables the use of reversers is not taken into account. For contaminated runways you could take their effect into consideration. Besides, it all has become a lot more complex now with the introduction of GRF, LDTA and what not.
I haven’t flown every aircraft out there of course but I think its mandatory to select at least idle reverse on most types. Not selecting idle-reverse upon touchdown, letting the engines spool down to ground idle and then finding out you need them, probably takes too long for them to spool back up. All the reverse restrictions at EU airports are usually referring to thrust above idle reverse. They also come with a note, unless necessary in the interest of safety. When the runway is wet or contaminated I consider that in the interest of safety. Especially in northern Europe this time of year there the braking action (or runway condition code nowadays 😵💫) can be quite bad.
Why would you need the engines after applying reverse thrust? I don‘t know the Embraer but I‘m pretty sure that once you go into reverse in an Airbus or a Boeing the chance to go around has passed. Autobrakes kick in, the planes are in ground mode etc. DH/MDA are there to make sure the runway is clear for your landing, you‘re going around if you miss the touchdown zone or reach a certain point of the runway or whatever but you don‘t close the reversers and push the throttles forward under any circumstances, do you? There are even additional hurdles to overcome to go into reverse, levers to pull up, moving the whole throttles or power levers over gates etc, this is a deliberate action that makes a following go around highly unsafe if not impossible. To my knowledge reverse is a purely economical consideration to reduce brake wear a bit (when used with autobrakes) and b) ensure that the throttles are definitely in the idle position.
No, its a misunderstanding. Indeed, on any aircraft I know off, you can’t reject the landing once reverse thrust has been selected. Meaning that up to the point thrust reversers are deployed you can actually still reject the landing, maybe runway conditions are worse than expected and landing distance is known to be critical, you might not know until you are actually on the runway? Maybe you landed far down the runway with not enough distance left to stop. Sure, you should have made the decision to go-around before ending up in such a mess, but could happen. Collision hazard might be a reason. Its not unusual during CAT III approach to make ground contact before positive climb is established, although this is more a balked landing rather than a rejected landing maybe. As soon as you deploy thrust reverser you indeed can’t reject the landing anymore. What I meant is this, if you do not select idle reverse, the engine will spool down to ground idle, from that point it takes time for the engines to spool back up should you decide you need reverse later on during the landing roll. I think this is the main reason most operators select at least idle reverse upon touchdown.
Don’t forget landing on contaminated runways. You are not allowed to take the effect of reverse thrust into account during the planning phase. For in-flight landing distance assessment however, for landing on a contaminated runway for example you are allowed to take thrust reverse effect into account. Apart from all the regulations, should you inadvertently end up on a runway with poor friction, its nice to have thrust reversers as brakes probably won’t do anything. Also rejected take-off is unfactored, sure its based on unfavorable conditions, but still there is no extra safety factor applied. Theoretically, should you take first action to stop at V1 during a field length limited take-off, applying maximum stopping performance without reverse, the aircraft comes to a stop with the nose wheel at the runway end. It would therefore be beneficial to apply reverse thrust, even if its only on one engine to create some extra margin (if the manufacturer allows use of reverse during single engine operation of course). So reverse thrust has more uses than just decreasing brake wear, during normal operations however you are correct.
Not quite, it should not be done, but its not impossible, the reverse gate or beta gate on turboprops usually only work one way. You can’t go into reverse or beta mode without lifting detents, but you can apply forward thrust effortlessly without having to clear any gate. Autobrakes will disengage above a certain Power Lever Angle (PLA), spoiler will automatically retract also above a certain PLA. So it is definitely not impossible or a hurdle to go from reverse thrust back to forward thrust and reject the landing, but it should not be done of course. Once selecting reverse thrust you are committed to a stop.
This is a really nice video on the topic:
Edit: now I think about it, I don’t know how it works on a Boeing with the little reverse levers. Maybe you can’t select forward thrust until reversers are stowed. My type rating on the Boeing 737 has been too long time ago, need to refresh 
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