To make it clear, the nose gear isn't counted as it would require us to calculate the co-efficiant of friction for different runways ect. which would require us to carry around an ungodly amount of charts and graphs. It does not imply that the wheel has lifted off the concrete. So on the ground you can only use the rudder and not the ailerons for all intents and purposes. In the air, you have the use of both rudder and aileron so VMCA is lower than VMCG.

got ya, now it make sense.so in theory Vmca is never really needed as Vmcg is greater then Vmca,hence I would never be in the air anyway at that speed, as Vmca is lower then Vmcg -> which is lower then V1 = I am still on the ground at Vmca speed.is that statement true?Thanks..

One other note about V1. The speed is predicated on stopping on the remaining runway WITHOUT the use of thrust reverse, ONLY maximum braking. Yes, on a shorter runway V1 will be well below Vr.

ONLY maximum braking.

AND spoilers...

To make it clear, the nose gear isn't counted as it would require us to calculate the co-efficiant of friction for different runways ect. which would require us to carry around an ungodly amount of charts and graphs. It does not imply that the wheel has lifted off the concrete. So on the ground you can only use the rudder and not the ailerons for all intents and purposes. In the air, you have the use of both rudder and aileron so VMCA is lower than VMCG.

Hi Ronan,With all respect I am not so sure Vmca is lower than Vmcg; mainly because VR has to be atleast 105% of Vmca. V1 just have to be equial or greater than Vmcg. and VR must be equial or greater than V1.For instance on the A320: VMCG: 109,5kts and VMCA: 110kts.So there is a small difference. (Impractical)Kind regards,

got ya, now it make sense.so in theory Vmca is never really needed as Vmcg is greater then Vmca,hence I would never be in the air anyway at that speed, as Vmca is lower then Vmcg -> which is lower then V1 = I am still on the ground at Vmca speed.is that statement true?Thanks..

in simple terms, rotate speed is above vmcg and vmca. In the DC10, if you were empty with only a few thousand pounds of gas you could have vr min problems. In this case rotate was lower than vmca. Rotate would then be bumped up to vr min.

One other note about V1. The speed is predicated on stopping on the remaining runway WITHOUT the use of thrust reverse, ONLY maximum braking. Yes, on a shorter runway V1 will be well below Vr.

actually in JAA certed aircraft reverse thrust is factored. I did'nt know this until we bought our first G550. It was certed first with the JAA.

Hi Ronan,and VR must be equal or greater than V1.Kind regards,

this is not necessarily true, Vr could be lower then V1.hypothetically / theoretically speaking , if you run a 738 on a 10Km runway (like those used for landing Space shuttles), Vr would be way before V1 ever comes up,as you ready for lift off way before you run out of RW to stop if you decide so.now if you look at it more realistically, if a Cessna or a small jet would take off at JFK airport (e.g. 12,000ft RW) it would be the same as my example above, the plane would reach Vr way beforeit runs out of RW to stop (V1 principal / the idea behind V1) .so I am not sure the Vr must be lower then V1.in that case V1 is insignificant / not needed.

Hi Ronan,With all respect I am not so sure Vmca is lower than Vmcg; mainly because VR has to be atleast 105% of Vmca. V1 just have to be equial or greater than Vmcg. and VR must be equial or greater than V1.For instance on the A320: VMCG: 109,5kts and VMCA: 110kts.So there is a small difference. (Impractical)Kind regards,

Sorry I meant to say generally, not always, my fault...Vr > 1.05 of VMCAV1 > VMCGBut out of technicality, VMCA < VMCG is possible if V1=Vr....I'm gonna need to get the books out for some of these questions...

this is not necessarily true, Vr could be lower then V1.

No, never is due to the ideas and principals behind those speed targets...V1 is always < Vr

...and V1 is always faster than Vmcg. And V1 can never be faster than Vr.Sorry, I forgot to click on page 2 before that last post.They never want you to abort once airporn, big nono in jets. In light twins however, that is a different story.

No, never is due to the ideas and principals behind those speed targets...V1 is always < Vr

well, this is more for "cosmetic" reasons or pilot confusion reasons, but it doesn't mean that V1 can not be greaterthen Vr physically.

They never want you to abort once airporn, big nono in jets. In light twins however, that is a different story.

no one was referring on aborting while airborne.we were talking about that when you get to a stage which you could lift off the ground (Vr), you could decide not to as you still haven't gotten to V1 yet as you got ages long RW to stop if you wish not taking offfor whatever reason you see fit.(see my example above).

V1 will be the greater of vmcg & critical engine failure speed(military), and in some aircraft rotate speed not to exceed tire limit or max braking speed. So in a practical sense v1 will not be be higher than rotate speed. Depending on the calculation process, v1 and rotate will be the same when the field is balanced. Even in this situation, v1 will allways be stated first "v1 rotate" all in the same breath. Following the procedure keeps you safe. In heavies, most guys will not abort above 100kts unless there is loss of control, thrust or a fuselage fire. Rotate speed is the game ender as you have achieved your goal of flying. After flying 7 different types of jets to include heavies, I've yet to see a procedure that gives a v1 that is higher than rotate. While in some cases one could state they have enough runway to stop, if the problem causes you to loose ground spoilers or anti-skid, you have no idea of what you need. Makes more sense to take it in the air at rotate and have time to see what you have and sort it out. Unless the aircraft is unflyable "all engine flame out or flight control hard over", i see no reason to abort at rotate. Even with a fuselage fire, i can do a oppossite direction landing and get back on the runway quickly.

You are on the track. In the real world the FMC or the performance manual accounts for the runway/airport conditions. Would be nice if this was factored in PMDG. In the Gulfstreams that I fly, there are take-off calculation pages that are part of the perf init section. Here i can add obstacles, climb gradients, runway conditions and configuration to calculate data and v-speeds. As long as my accel stop/go is equal to or less than runway available, i am good. This only ensures that i am not field length limited and i must verify i can clear obstacles and climb gradients. Our fleet also have performance manuals that can be used to calculate the informance in the case of FMS failure of the the performance module. Would be nice if these factors were added to PMDG. Alot of companies will have special engine out procedures created at certain airfields in order to increase takeoff weights when limited by climb gradients and obstacles. These procedures provide an escape route in the event you loss an engine after V1. I just used one these procedures at MMMX due to the high PA and gradients.

You guys use performance manuals still? I think I used them years ago when I was flying PA31's.....no wait...we used a Whizwheel. On my entry level jets we used UltraNav; a computer based performance calculator. The last corporate jet I flew was a Lear 45, same thing; UltraNav but with the addition of APG. Interesting tool that APG.

You guys use performance manuals still? I think I used them years ago when I was flying PA31's.....no wait...we used a Whizwheel. On my entry level jets we used UltraNav; a computer based performance calculator. The last corporate jet I flew was a Lear 45, same thing; UltraNav but with the addition of APG. Interesting tool that APG.

We use afmatic for performance planning and the FMS calculates performance. There are extreme cases when we will use the manual, for example contaminated runways(RSC). The manual is tabulated but there are charts for accel/stop distances. We have issued IPADS for charts and manuals but we do maintain a performance manual in the flight department and on each aircraft just in case. When i was in the airforce, we used performance manuals routinely when i was flying c-141s and kc-10s.

Actually being airborne has allot to do with it. In theory V1 can be greater than Vr but this is the main reason it never can be. Vr is rotate to go flying. The main point is that V1 is the decision to abort or go flying. Past V1 you go flying unless the airplane will not fly, but that is the only reason. In a light twin you have an "airborne V1" because the airplane is not guaranteed to fly under part 23. All FAA part 25 aircraft must be guaranteed to fly after V1 and they are designed to continue the remainder of the takeoff OEI or on fire or what have you. To abort when airborne in something like a 737 is way more dangerous than dealing with an engine fire and continuing after the tires (even the nose gear) leave the ground. Correct me if I am wrong but that is the principal reason why V1 can never come after Vr.

Actually being airborne has allot to do with it. In theory V1 can be greater than Vr but this is the main reason it never can be. Vr is rotate to go flying. The main point is that V1 is the decision to abort or go flying. Past V1 you go flying unless the airplane will not fly, but that is the only reason. In a light twin you have an "airborne V1" because the airplane is not guaranteed to fly under part 23. All FAA part 25 aircraft must be guaranteed to fly after V1 and they are designed to continue the remainder of the takeoff OEI or on fire or what have you. To abort when airborne in something like a 737 is way more dangerous than dealing with an engine fire and continuing after the tires (even the nose gear) leave the ground. Correct me if I am wrong but that is the principal reason why V1 can never come after Vr.

Let's put it simple but clear, I was not talking about aborting after leaving the RW (so let's not bring that up again).The rotation of the aircraft begins at Vr, which makes lift-off possible, at the end of themaneuver.one can decide not to at that speed and abort.this means Vr is a point on the ground which would lead you to be airborne.simple answer to your replay which you said it yourself.Vr is rotate (well it is the time you should rotate to get airborne), V1 is a decision Velocity rather to take off or not.if Vr is reached before V1 ever does (as I never had to get to the point of a go no go, as I have ages long RW to stop if I wanted to even when I reached Vr).I never committed to take off. and yes it could happen - V1 could be greater then Vr.and I'll give you a real life example.if you take a Cessna 172 on a 14,572ft RW at JFK (13R/31L). ok, how long do you think the Cessna would run/roll until it reaches Vr?500m?, 800m? - 1km Max.Yet the Cessna has still 3+Km of RW which he can stop if he wishes to, even when he reaches the Vr state/speed (which he needs to rotate).hence V1 doesn't really come to play here as he always have enough RW to stop.now I think I understand your point of view why V1 has to be lower or equal to Vr.as the Vr becomes your decision speed (go/no go).it all ends up with the question, what is the exact defenestration of V1? 1) is V1 a point of which the pilot decides (to his desecration) rather he is going airborne or not?2) is V1 a point which behind this point of which the pilot is committed to take off as there just not enough RW to stop?now if the answer is No 1, then you are right , Vr becomes V1 also, as that is the point where the pilot decided rather he rotates or aborts.that means V1 can not be greater then Vr.however if the answer is No. 2, V1 could be greater then Vr (the Cessna example above).what I always read and understood is that V1 is the maximum speed at which a rejected takeoff can be initiated, in the event of anemergency, as there is just not enough RW to stop behind that point (well 2sec' later then that point).therefore V1 could be greater then Vr (Cessna Example above - he was never committed, it was his decision to Rotate or not at Vr).

Hi Joel,“JAR/FAR 25.107 V1, in terms of calibrated airspeed, is selected by the applicant; however, V1may not be less than VEF plus the speed gained with the critical engine inoperativeduring the time interval between the instant at which the critical engine is failed, andthe instant at which the pilot recognises and reacts to the engine failure, as indicatedby the pilot's initiation of the first action (e.g. applying brakes, reducing thrust,deploying speed brakes) to stop the aeroplane during accelerate-stop tests.”Regards,