What is reverse thrust? Explained by CAPTAIN JOE

INSTAGRAM FLYWITHCAPTAINJOE: https://goo.gl/TToDlg MY WEBSITE: https://goo.gl/KGTSWK Today´s question is another favorite of mine. What is reverse thrust and when do you use it? Okay, I´ll break it down for you to the absolute basics. Reverse thrust is used to slow down the aircraft on the runway after touchdown. There are three main components which slow down the airplane on the runway: Primary Braking with disc or carbon brakes similar to your car Secondary with reverse thrust Thrid with aerodynamical braking with the ground spoilers So we have two words in reverse thrust. “Reverse” cause the turbines output is being guided into the reverse direction and as you might not know we apply "thrust" in order to increase the braking action. So let´s look at this video to see what happens at touch-down. Here you can see engine number one of a Airbus A320. At touch-down these flaps open up, so called “reverser doors”. They act as guiding vanes in the mid section of the bypass-channel of the turbine and force the accelerated air of the fan to blow into the opposite direction. Now these reverser doors don´t open automatically at touch-down, no you lift up these little levers which will activate the hydraulic system to apply pressure to the actuator which then opens the reverser doors. Keeping the levers in this position only give you “Idle reverse”, but as soon as you move the levers to the aft position, the engine will spool up creating more thrust increasing the reverse output. The engines will increase thrust up to 70% which then resembles in “Full reverse thrust”. I know it´s odd to think that you would apply thrust again just after touch-down. You can definitely hear the difference between “Idle” and “full reverse thrust”, trust me :) Using the reversers significantly decrease the landing distance, varying between aircraft, weight and environmental factors. If you look at this great video of here, showing a Boeing 747 touching down and applying full reverse thrust you can clearly see how the water on the runway gets blown forwards. I actually experienced that myself landing on a snow covered runway, we applied full reverse thrust and you could literally see the snow blowing infront of the aircraft. So when do you use reverse thrust? Using “idle reverse” at touch-down is mandatory by many aircraft manufactures and airlines. First and far most to immediately decrease the aircrafts speed and to stabilize the aircrafts roll out plus to reduce brake usage. Landing on wet or snow contaminated runways using reverse thrust is absolutely vital to decelerate the aircraft and preventing it from skidding and keeping it in a straight line. Full reverse thrust is not permitted at some airports due to noise abendement procedures or at least restricted in between hours from here to then. Nevertheless pilots can use full reverse thrust when deemed necessary, but might have to state their decision in a report. Airplanes with wing mounted engines may only use full reverse thrust until slowing down to a specified speed, cause using the reverser below that speed could blow up loose gravel on the runway which could get sucked into the engine and damage the turbine. For example in an Airbus A320 you would have to reduce "full reverse thrust to idle reverse" at 70 knots, and retract the reverser at speeds below 40 knots. There are many different reverser types out there, but all work after the basic principle by forcing the air or even the exhaust into the opposite direction. So I hope I´ve answered another aviation related question for you. If you have a question that´s been on your mind, don´t hesitate to write me, therefore subscribe my channel, check out my website and spread the word! Farewell your Captain Joe Info: Fairly often you see executive jets using reverse thrust during taxi, to reduce break usage whilst rolling down sloping taxiways. Cause of their high mounted engines pilots don´t need to worry damaging the turbine due to gravel on the asphalt. And the well know MD80 with her rear mounted engines use to have a power back procedure, where they used reverse thrust to back out of a gate position. I´m not 100% if that procedure is still around? Maybe you know? To me that looks very dangerous. Equipment I use: Camera: http://amzn.to/2nEHPDM Microphone: http://amzn.to/2nff2oF Lights: http://amzn.to/2nEPGkU

Comments

John Sampson: I always find it hilarious that there are always a few know-it alls, who think they know more than everyone else, or even the experts. Now you know who the typical arseholes really are.

Pietro Di Meglio: Man, i'd love to be a pilot

Rafa Petterson: Why don't you just turn the engines around? That'd be cooler ;)

otosflashymoon: I just wish you would use a lapel mic.

scoobydoobytoob: Thank you for the informative videos Cap'n Joe! I do have a question regarding tri-jet designed airliners, which I understand that fuel costs and larger engine reliability today helps to negate my inquiry?! Why do manufacturers not have a mid-size tail engine built into all dual engine airliner and have dual mid-size tail engines built into every four engine Jumbo Jet or A380 airliners and above, only for emergency uses like when both dual engine planes fail on/after takeoff​ to keep enough air speed until being able to safely land? Or, having the dual mid-size engines below the tail also assisting takeoff and, in the unlikely event of all four engines failing in inclement weather in flight over the Ocean, in order to aid the plane to get to a safe landing on land? Is this an unnecessary idea or would this help in emergencies?? Also, another specific reason I ask why we do not have a stacked engine design in airliners is, when my wife and I flew into La Guardia last year, we were seated in the rear of the plane and due to high wind speeds, cross winds and up/down forces that day the tail was all over the place and we were terribly frightened! Would a smaller tail jet engine help to control the descent at 3 points of propulsion or are just two or four engines on the wings enough??

daffidavit: Dear Captain Joe: I remember many many years ago, probably on a DC-9, the Captain would use reverse thrust to go backwards from the boarding gate at Melbourne Fl. Airport. I'm talking about the early 1970's when I was a student at FIT. I was also a certified private pilot at the young age of 17, so I probably knew what I remembered. So If my memory serves me correctly, you are right, the "Eastern Airline" DC-9's would push back using reverse thrust from the gate without the help of a "tug" for push back.. I know it happened because I know I experienced it. I just can't confirm with certainty which airline did it. I would bet it was Eastern Airlines at the time because that was one of the two airlines going from Kewr to Kmlb at the time. DPA

injahnet: How about a turbo prop reverse?

Raidzor つ ◕_◕ つ: Joe, or anyone else that know to answer these 3 questions:
1)Can reverse doors be opened without applying any braking power?
2) Is idle reverse actually using idle power or it still applies some thrust?
3) Can the reverse thrust be applied right before touchdown? Let's say under 10 feet?

Rajeev Prv: Hi joe, I have a question. When one of the engines of a 2 engine plane shuts off, will one of the wings not overshoot because the other wing is not having the thrust. How is this managed?

Andrew Hills: I wanna be an air traffic controller. Out of curiosity, ab how much of the flight time as a pilot is spent communicating with an atc

TJ Devereaux: Thanks Joe, I've always wondered exactly how it worked. I've flown hundreds of times but never knew! Thanks again, happy trails 🛬🛫✈️✈️✈️✈️✈️

HiGaming - Roblox and More: after hitting the runway 0:09

tbpom1003: Have you gone backward with reverse thrust?? haha Thanks for the awesome explanation!!

Neel Banerjee: Can reverse thrusters be used to reverse the plane on the tarmac instead of the push back truck?

nirmal kumar: Hello Captain Joe, I recently traveled to India in 737 before taxing I heard some wearied noise, later I noticed the same noise before taxing i.e., exactly after the doors are closed. Could you please explain me what it might be. Thank you

Peter Morgan: For anyone who's interested, this is a brilliant example of reverse thrust in action. Thanks for the video Captain Joe!

Alex Derus: What about when a plane does a reverse thrust move known as a "power back?"

AeroWilly 974: hi
thanks for this video Captain !
+1 subcriber and like 😉
good flights 😀✈

Rare Form: frust

Aslanbek Aslanbayev: My report would say:
I used full reverse thrust to piss off these pompous kniggets who think airplanes are evil because they make noise.

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