V speeds are the routine numbers a pilot plugs into his FMS (flight management system) before take off. In fact, fancy airplanes tell you the V speeds after you tell it things like weight, temperature and your mood for the day. Ok the last part is not true, but in the future, that could be a factor.
Whether it’s the air over the wing of your airliner or across your helicopter’s blades, speed is what makes you fly. Training is all about creating familiarity and comfort, so we give them names like V1 and Vr. After their first simulator flight, new jet pilots focus on a variety of emergencies, and knowing the role of “V speeds” is key. This post is about the demarcation points in your flight these speeds play, and how they keep you safe.
“The Lear Loves Speed” said an overly amped South African to me once.
His statement was based on multiple upgrades from slower to faster machines he had recently experienced… and learning that his Lear 35, the jet of jets – had hammered home the importance of speeds. He had landed in some short spots in Angola – and he didn’t want his speed hungry machine taking him to places it didn’t belong anymore.
The best way to understand these key velocity (V) demarcation points is to start from the bottom up. Understand them and how they apply to different parts of your flight and many non-pilots reading this will feel a little more aeronautically savvy after reading the definitions and seeing how they match their spots in the chart.
The big secret with flying jets is to survive the simulator. Do that and you’re more or less good to go. Some simulator time is spent hand flying (but mostly autopilot flying) and being a rockstar on speed management is one of the corner stones of good airmanship, familiarity and comfort with the airplane.
Speed knowledge and comfort is necessary since it affects your “go / no go” decision making process.
Decision Speed – V1
V1 is in many ways, a metaphor for life, business, relationships and more.
It has many names, but “decision speed” is perhaps the best because it is a moment where decisiveness is required: Hit the brakes, or go? In training all of the engine failures will occur at this speed. Not before or after – since then the decision is too easy. When it happens *at* V1 – you must decide:
STOP: If you’ve begun your take off roll and you have not yet accelerated to V1 then the manual, book, common sense, your lawyer, the flight computer, will all tell you one thing: Stop the airplane on the runway.
GO: If you are within 3 knots of V1 or have accelerated past it then you have no choice: You must go.
The key with being near V1 is that if you are in doubt – the reflex should be to just go. The rationale is that once you are airborne, life is far less complicated than coming to a muddy stop in the weeds off the end of the runway. Jet aircraft fly and accelerate just fine on one engine, despite the loud messages the airplane screams via its alert system.
V1 is an important speed since it is *the* speed that dictates the definition of Balanced Field Length (BFL)
The most important thing about V1 is recognizing that you’ve passed it and there is no going back. No matter what happens at V1, engine failure or not, your next mandate is to get to Vr because you are now committed to being airborne.
Vr: Getting Some Air
The next speed is where the runway is left behind – as you (r) rotate off it. Vr is the speed at which you “rotate” the horizontal axis of the aircraft off the runway by pulling back on the stick. In the world of heavily automated flying, this is one of the rare parts of the flight where the pilot actually has to manually do and manage everything with the controls before it all gets turned over to the autopilot. The act of keeping the airplane on the center line (with your foot rudder pedals) and then pulling back to get it airborne is the last act typically before engaging the autopilot at 500 feet above ground level (AGL) which is a legal limitation of most autopilots after take off.
Once the aircraft passes V1 and hits Vr, you are going to leave the runway and begin accelerating even faster. This all happens as the pilot pulls back on the yoke or stick and pitches the nose up from 7 to 15 degrees above the horizon. At Vr, this upward angle of the wing, causes the airplane, even on one engine, to leave the runway and accelerate.
V2 is Safety
If 1 is for decisions, then 2 is for staying safe. Referred to as “safety speed” V2 is the optimal speed you must pitch aircraft’s nose to in order to keep climbing, assuming you’ve only got one engine. Once you’re showing a positive rate of climb, the first order of business is to retract the landing gear, since it is slowing you down and you need to get to V2 and 400 feet AGL. Note: If you are flying alone in a jet it is important to have blind familiarity so that you can actuate the gear without looking down for it. (This critical time is not one when you can take your gaze of keeping the airplane right side up and going up.)
When everything is running fine you can zip into the climb at V2 + 5 to 20 knots, but for training purposes you’ll be focusing on your survival and grace by using V2 to get the airplane to 400 AGL. Once you hit 400 AGL it is a chance to nose the aircraft over to a more level altitude and gain speed so you “clean the aircraft up” (this means retracting things like flaps) and accelerating to Vfs.
Vfs – Final Segment, Finally
The final segment (Vfs) climb speed is typically attained quickly in the period where you’ve leveled off at 400 feet AGL at V2. Keep in mind, even if you struggled to hit V2 as you get to 400 feet AGL, the moment you nose the aircraft over it will begin to accelerate to Vfs. Once you hit Vfs, pitch the aircraft up into a climb again to get to a safe altitude.
Vref – Reference
Reference speed, or Vref, is a number that changes based on aircraft configuration, wind conditions and other considerations, such as aircraft weight and the level of automation in use. Vref is a key speed for the crew to know during the landing phase (and have prominently displayed on the airspeed tape or gauge) since it is defined as a 130% multiple of the aircraft’s stall speed in a specific landing configuration.
If you’ve ever wondered “ Could you land the airplane if the crew was incapacitated?, ” then Vref is an important number to know and understand.
Vref matters since strict focus on it (and staying above it) keeps the airplane safe between initiating the approach and landing. Fall below Vref and you are now entering the realm of becoming a brick. The danger of ignoring Vref was most recently exemplified by Asiana flight 214 in San Francisco in July of 2013. Despite three sets of eyes on the situation (and a beautiful day and conditions to boot) the level of distraction, complacency and trust was so high that no one thought to speak up as speed bled dangerously low, until it was too late.
The chart below also shows how aircraft are certified using Vref. Fly 50 feet above the landing threshold at Vref at a given weight, land, and come to a complete stop, and that is your defined (note: legal) landing distance requirement. Engineers, the FAA and lawyers then add percentages to that number typically so that we still stop on less than perfect days. If you are flying with me, I’ll even add more to the legal requirement if I can – especially if I’m new to the airplane.
Riding in Back
For those passengers that are curious about the nuances of the flight, you can see and feel some of these speeds as they happen. When the take off roll begins … while you don’t know it, all eyes up front are on V1 and getting to it …. incident free, or … looking for a reasonable excuse to reject that take off. Once the aircraft has reached V1, you know when Vr is happening since you watch the ground tilt out the window as the nose lifts off. Then it is V2 + 5 to 10 knots… and that’s your steep first climb. 99% of you reading this leave from airports that have noise abatement procedures and be flying in modern powerful twin engined jets, so the first bit, after take off, always seems like the ground goes away quickly. This steep climb ends with a very noticeable level off (usually around 2000 to 3000 feet) where the aircraft is cleaned up and continues a more gradual cruise climb.
Once you’ve reached that point, you’ll be glad to know that the rest of the flight, no matter how plagued with problems it might be, is a very casual affair for those up front. Nothing requires more careful risk and speed management than taking a heavy, slow and low airplane safely into the first part of its trip.
Once the take off is over, whether you did it on one engine or two, the hard work is done with the caveat that all the key players are alert when it is time to reconnect with planet earth.