Why Do Airliners Rarely Use Full Thrust On Takeoff?

Wherever it is in the world, an airliner’s departure will typically be an impressive display of power. The impressive sight, paired with the roar of engines, is due to the forces needed to lift the aircraft’s weight off the ground. Despite this, an airliner will rarely use its full capabilities on takeoff as far as thrust is concerned. But why is this?

Video source links:

Simple Flying:

Follow us on social media:

#aviation #flight #avgeek #airlines #flying

[clarkneil]

Also worth remembering that a twin jet can still climb after take off with just one engine operating

[aerflyer]

I actually didn’t know that pilots don’t put full thrust on at takeoff. If I’m playing a flight simulator, I always use full thrust. Guess it’s time to change that 🤣

[flyboy]

Meanwhile in Infinite Flight:

*777 rocketing takeoff at full 100% thrust at vs +7000 ft/min. on a short London-Heathrow to Paris-Charles de Gaulle flight*

[Giggachad]

I really love these videos. Keep going!!

[matthewbarry]

Finally you’re answering the important questions lol

[philipkudrna]

The standard take off thrust is a „flex“ setting, which results in a reduced take off thrust. However, the pilot flying can always push the thrust lever to „TOGA“ (Take off/Go-Around), which will make available maximum thrust (but it might take some seconds for the engines to spool up, which is why at landing, the plane usually lands with higher thrust on engine and flaps deployed rather than idle thrust gliding, which would make it impossible to swiftly spool up the engines in case corrective action is needed.

[richardmueller]

Another very informative video Simple Flying! Keep 'em coming!

[burntsider]

Airport elevation, barometric pressure, temperature, weight, wind direction and speed, noise abatement, fuel consumption, runway length.

[kingjames]

Hi-Bypass engines used on today's aircraft produce so much more thrust than the jet engines of the 1950's-70's and so full power take-off's are not necessary. It is neat that full power is available when needed but for the vast majority of flights, it's just a waste of fuel and increased noise levels inside the cabin and on the ground. The motto is, have more than you need but use just enough to do the job.

[beatrice]

I was a flight attendant and I always thought they used full thrust. Especially on the 747s

[skyserf]

1:18 During systems class many moons ago we were shown a US Air Force study that showed a significant increase in the possibility of engine failure during takeoff if full thrust is used for takeoff. Max power takeoffs are also sometimes required by maintenance.

[dennislear]

During a stint in the ual engine shop in early '70s watched 747 JT9 hot sections fall in pieces on the floor, shoveled it into a bucket. They then added water injection seemed to help.

[ax_pilot]

I knew it already😅, but for those who don’t, you’ve summarized it very good

[suddhojitgon]

I did not have any idea that planes do not utilise full power for take off before watching this video. Thank you so much.

[KarmaFlight]

Takeoff in a lightweight 747-8F is quite a thrill. Even our heavier takeoffs often include a de-rate. Keeping a big jet on the runway, if an outboard engine rolls back, is a handful at low speeds.

[LoydChampion]

I did know this. I can also thank the extra thrust that a 757 can provide. It was well used on a flight I was on out of LAX one morning when there was a runway incursion. The captain hit the full thrust and lifted early. I saw the tail of another aircraft under the plane I was on at about 50 feet below. The pilot then lowered the nose to level to gain airspeed. When we went over the beach we were still pilled into the seat and I think we went by the beach at about 300 feet and with the speed climbing fast, he then nosed up to continue on with the flight. The pilots earned their money that morning.

[justdave]

I always thought they used full power on takeoff. Thanks for educating me!

[pirahna]

Actually, you can’t override a de-rate on most jets. There are two types of reduced thrust takeoff: A flex takeoff (or assumed temperature takeoff on a Boeing) is where you enter a higher outside air temperature into the FMC, which tricks the computer into setting a lower N1 or EPR limit for the takeoff. This type CAN be overridden in the event that more power is needed.

A de-rated takeoff is where the engines are given a reduced thrust limit, which cannot be overridden until climb thrust is selected.

Both methods are inherently safe, and they must still meet all required climb gradients, assuming an engine were to fail at V1.

[jamesmcdonnell]

The late great Freddie Laker was the first airline boss in the world to introduce derated take offs . Being originally an aircraft mechanic he realized full power take offs were seldom necessary particularly when there was a strong head wind.
He had his staff make take off tables with regard to wind speed etc at every airport he flew from and over time engine manufactures realised his plane engines required less overhaul, had less wear and needed less maintainence than other airlines using similar engines and planes. plus he saved on fuel costs.

[daveb]

In an A380 cockpit video I noticed climb thrust was higher than thrust used for take off. Do any other airliners do this?