Aviation Know-How Series #3: Know When to Stop – V Speeds Easily Explained!

Hello dear readers and aviation enthusiasts, after being busy with choosing the photos for the second round of the Spring Photo Contest, it is now time to get into the Aviation World again, so, let us take off!

Today, we will have a look into an airliner’s takeoff run – a highly dynamic situation! Errors can occur anytime. But how does the Pilot in Command know if it is safer to abort the take-off after a tire burst (for example) or to get off the ground because there’s not enough runway left to stop the aircraft safely? How does he know when to pull the yoke back and to lift off and what speed he has to maintain to climb safely, even with a lost engine?

The Takeoff Speeds!

That is where the so-called V Speeds come into the game! There are plenty of them, but I will concentrate on the three most important ones today:

  • V1
  • Vr
  • V2

Maybe some of you have seen a video from out of the flight deck, or even took a flight on the Jumpseat and heard the different call outs in the takeoff run!

V1 – The Decision Speed!

Aeroplanes use runways to take off (Aaron, you don’t say? 😀 ). Unfortunately, these runways are limited in length. Sometimes, takeoffs have to be aborted, there a many possible reasons for that. It could be an engine failure, a burst tire, or an avionics fault (or the pilot decides he needs more coffee). If one of these events occur, the pilot stops the aircraft on the runway, using the aircrafts spoilers, reverse thrust and brakes – But only before reaching V1!

V1 is the maximum speed at which a rejected takeoff can be initiated! It is sometimes also called the critical engine failure speed! After reaching this speed you go in the air, no matter what, unless the aircraft is not controllable anymore (a wing falls of, or a severe fire), because the runway length remaining would not allow to brake safely anymore. You heard right: it is safer to take off with one engine left than to abort a takeoff after V1! Modern airliners can easily fly with only one engine left! (More to that in another article).

Vr – The Rotation Speed

This one is easy: Vr marks the speed when the pilot starts to pitch up the aircraft’s nose in order to lift off the ground! (Usually with a speed of 3 degrees per second in order to avoid a tail strike!). This process is called rotation in aviation.

V2 – The Takeoff Safety Speed

This speed is the minimum speed required to climb safely even with an engine failure after V1! Until the acceleration altitude is reached, the climbing speed often is V2+10 knots!

The calculation of all these speeds are very difficult, since many factors have to be taken into account – the runway length, the aircraft’s weight, the temperature (jet engines are more efficient in cold temperature), the winds, etc. etc, but it is very important to do these calculations thoroughly – errors may lead to a to early takeoff (danger of a stall), a tail strike or high-speed takeoff abortion, with too less runway left!

I hope I could help some or the other with this little article, if there are questions left, hit the comments below!

Cheers, and always three greens,

AP

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8 thoughts on “Aviation Know-How Series #3: Know When to Stop – V Speeds Easily Explained!

    1. Indicated airspeed is the crucial one on the ground, the same that is shown in the PFD. That is one of the reasons why an airspeed indicator cross-check is done at,80 knots 🙂

      1. i so want to hotrod a 1049-G wiht d27 propfans and contrarotating props and hss-glare sandwich the structure of hte bird. wonder also how a concorde would take four f414-epe turbines wiht a static weightsaving airinlet

  1. Great.. I’ve flown the 737NG in a real-world sim and enjoy flight simmers and this guide’s captivating. You do a good job at bringing aviation terminology down to layman terms for everyone to understand : )

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