Calling V1 five knots early?

[PeanuckleCRJ]

Just curious the difference between V1-5 and "Most guys remove their hands from the thrust levers a couple knots before V1 since there's no time to make the decision at that point."

You're not calling V1 at an arbitrary point when V1 hasn't happened yet. If you're calling V1-5, that's not V1. The time to make the decision is not always 5 knots. It might be a couple, depending on acceleration rate.. it might be more than 5.

I don't like arbitrary numbers.

 

[derg]

Spot on. Most guys remove their hands from the thrust levers a couple knots before V1 since there's no time to make the decision at that point.

I don't like this V1-5 stuff... pretty dumb if you ask me. It's a slippery slope on selecting arbitrary numbers that aren't the actual performance numbers. Besides, more and more modern aircraft have auto V1 callouts. Are you guys bugging V1 5 knots low on those aircraft?

I kind of like the military thing of calling "go" at V1. That's really what you're doing.

I'm hands-on-thrustlever until about 80 knots, above 80 knots when things start getting a little bumpy, my hand goes from a "grip" to a flattened hand held a few cm above the thrustlevers approaching V1, they're moving away from the thrust lever because I largely don't want a "false positive" from the FO and be spring-loaded to abort.

I've seen one high-speed RTO, like a few knots under V1 and we blew a tire, FOD'd an engine and it was a nasty experience. Imagine a fat MD-90 in SLC full of people and bags. You could have pulled the brake pads off and hosted a Mongolian BBQ party on the ramp.

In retrospect, the plane was OTS, needed to have the engine scoped, tire replaced, probably a new set of brakes and all over a fairly minor item.

 

[PositionAndHold]

You're not calling V1 at an arbitrary point when V1 hasn't happened yet. If you're calling V1-5, that's not V1. The time to make the decision is not always 5 knots. It might be a couple, depending on acceleration rate.. it might be more than 5.

I don't like arbitrary numbers.

Maybe I'm reading it wrong but what you just wrote is the definition of arbitrary. If you can make any go/no-go decision within a couple knots you're a way better pilot than me. It probably depends on the airplane and the V1-Vr spread. But if your calling it minus five knots every time in the same airplane the results should be a lot more consistent than "it depends".

 

[PeanuckleCRJ]

I'm hands-on-thrustlever until about 80 knots, above 80 knots when things start getting a little bumpy, my hand goes from a "grip" to a flattened hand held a few cm above the thrustlevers approaching V1, they're moving away from the thrust lever because I largely don't want a "false positive" from the FO and be spring-loaded to abort.

I've seen one high-speed RTO, like a few knots under V1 and we blew a tire, FOD'd an engine and it was a nasty experience. Imagine a fat MD-90 in SLC full of people and bags. You could have pulled the brake pads off and hosted a Mongolian BBQ party on the ramp.

In retrospect, the plane was OTS, needed to have the engine scoped, tire replaced, probably a new set of brakes and all over a fairly minor item.

That's great technique.

I've heard of guys doing RTOs in fifi, and it's apparently like you hit a freaking brick wall. Several weren't able to get the engines into reverse the deceleration was so rapid (they were hanging from their shoulder straps!).

One of the senior APD's described it as "ABORT" (WHAM) "I have the aircraft" (it's already stopped). "oh... spoilers up.... 80 knots."

 

[PeanuckleCRJ]

Maybe I'm reading it wrong but what you just wrote is the definition of arbitrary. If you can make any go/no-go decision within a couple knots you're a way better pilot than me. It probably depends on the airplane and the V1-Vr spread. But if your calling it minus five knots every time in the same airplane the results should be a lot more consistent than "it depends".

I suppose you can read it that way- the reason why I'm calling V1-5 every time arbitrary is because the real world is gray in regard to reaction time. Humans vary as well as the conditions.

For example, acceleration rates vary, sometimes quite considerably from a nearly empty plane to one at maximum takeoff weight at a hot/high airport. The time that it takes to go through that 5 knots in MEX in the summer at MTOW can be double or more the amount of time that it takes to shoot through that 5 knots on an empty plane at sea level when it's near freezing.

Make sense?

 

[derg]

Maybe I'm reading it wrong but what you just wrote is the definition of arbitrary. If you can make any go/no-go decision within a couple knots you're a way better pilot than me. It probably depends on the airplane and the V1-Vr spread. But if your calling it minus five knots every time in the same airplane the results should be a lot more consistent than "it depends".

Depends on the airplane.

Most modern airplanes "inhibit" particular alerts depending on your phase of flight and speed.

Above 80 knots to V1, in our flavor of "French Hussy", you're not going to hear a peep out of anything besides a fire ("bing!bing!bing!" *red light*) or engine failure ("bing!bing!bing!" *red light*). The way our airline's culture works, hearing "v1" means you're going on an airplane ride. In our culture, knowing a call is a few knots before may mean looking down, analyzing what we really have and, well, you'll be above V1 anyway. Yes, that will vary depending on the corporate culture, but that's our truism but not a universal truism.

 

[MikeD]

Depends on the airplane.

Most modern airplanes "inhibit" particular alerts depending on your phase of flight and speed.

Above 80 knots to V1, in our flavor of "French Hussy", you're not going to hear a peep out of anything besides a fire ("bing!bing!bing!" *red light*) or engine failure ("bing!bing!bing!" *red light*). The way our airline's culture works, hearing "v1" means you're going on an airplane ride. In our culture, knowing a call is a few knots before may mean looking down, analyzing what we really have and, well, you'll be above V1 anyway. Yes, that will vary depending on the corporate culture, but that's our truism but not a universal truism.

Bolded for truth.

 

[derg]

That's great technique.

I've heard of guys doing RTOs in fifi, and it's apparently like you hit a freaking brick wall. Several weren't able to get the engines into reverse the deceleration was so rapid (they were hanging from their shoulder straps!).

One of the senior APD's described it as "ABORT" (WHAM) "I have the aircraft" (it's already stopped). "oh... spoilers up.... 80 knots."

She does stop in the simulator, its pretty amazing.

When I was checking out on the 330, as flying pilot, when captain called "ABORT I HAVE THE AIRCRAFT!" by the time I got my head wrapped around it, I missed the abort speed, missed the spoiler/speedbrake ECAM, had to revert to the DECEL light on the autobrake button, then it was 80 knots and I just threw my hands up because I just felt useless as it was so fast.

 

[PeanuckleCRJ]

Well put, @Derg!

 

[PositionAndHold]

I suppose you can read it that way- the reason why I'm calling V1-5 every time arbitrary is because the real world is gray in regard to reaction time. Acceleration rates vary, sometimes quite considerably from a nearly empty plane to one at maximum takeoff weight at a hot/high airport. The time that it takes to go through that 5 knots in MEX in the summer at MTOW can be double or more the amount of time that it takes to shoot through that 5 knots on an empty plane at sea level when it's near freezing.

Make sense?

I think we're all actually on the same page. As long as the crew is conditioned so when they hear V1 they're going flying, I think it all ends up being equal. But say at V1-5 the PNF calls "engine fire". By the time the PF reacts you're probably pretty close to Vr, even larger airframes, no?

 

[PeanuckleCRJ]

She does stop in the simulator, its pretty amazing.

When I was checking out on the 330, as flying pilot, when captain called "ABORT I HAVE THE AIRCRAFT!") by the time I got my head wrapped around it, I missed the abort speed, missed the spoiler/speedbrake ECAM, had to revert to the DECEL light on the autobrake button, then it was 80 knots and I just threw my hands up because I just felt useless as it was so fast.

Remember, in the sim, it's rocked all the way back for T/O acceleration. It has to swing forward for the decel sensation, which takes a while. In real life, that decel sensation is instantaneous!

 

[PositionAndHold]

Depends on the airplane.

Most modern airplanes "inhibit" particular alerts depending on your phase of flight and speed.

Above 80 knots to V1, in our flavor of "French Hussy", you're not going to hear a peep out of anything besides a fire ("bing!bing!bing!" *red light*) or engine failure ("bing!bing!bing!" *red light*). The way our airline's culture works, hearing "v1" means you're going on an airplane ride. In our culture, knowing a call is a few knots before may mean looking down, analyzing what we really have and, well, you'll be above V1 anyway. Yes, that will vary depending on the corporate culture, but that's our truism but not a universal truism.

Unfortunately ours only inhibits nuisance CAS's above 40kts.

 

[derg]

Bolded for truth.

That's the kicker with these discussions, we're all taught as per our individual cultures the one true way to do something, but it's different at every airline.

Put a CHQ E145 FO in with a EGL 145 FO and it will form an Gnash Cluster with the "what are you doing? What are YOU doing?!" back-and-forth.

There's a reason why NASA/AMES would group UAL 757 pilots with UAL 757 pilots and DAL 757 pilots with DAL 757 pilots when they were conducting ADS studies, they just didn't want to waste an inordinate amount of time having to re-invent the already re-invented wheel.

I'm drinking a beer so I'm rambling, but this is a good discussion.

 

[PeanuckleCRJ]

I think we're all actually on the same page. As long as the crew is conditioned so when they hear V1 they're going flying, I think it all ends up being equal. But say at V1-5 the PNF calls "engine fire". By the time the PF reacts you're probably pretty close to Vr, even larger airframes, no?

We are, and I edited my post to make what I was saying a bit more clear after you quoted it.

I just don't like the "it takes 5 knots to make a decision" thing when the time to go through that 5 knots can vary quite dramatically. Additionally, the time to recognize and make a decision can very depending on what happened. That's too much variance for me to consider 5 knots the end all be all.

On all the transport jets that I've flown, we have the inhibit function above 80 knots, and say for an engine fire... it's not someone calling it out. It's immediate red lights and a bell. Your reaction to that is pretty stinking lighting fast.

Reacting to an engine flameout on the other hand is considerably slower since the engine slowly unspools. You'll first notice it in the yaw and then the generator changeover. Then the caution will finally light up. Hence my emphasis on the variance.

And to answer your question, many times V1 and Vr are equal for us.

 

[derg]

Like when I watch these guys in a 320:

http://www.world-of-swiss.com/en/swiss-cockpit

I can sort of get the flow of what they're doing, somewhat, you just couldn't drop me in with that crew and have any large amount of comfortable operational commonality.

Edit: But SouthernJets flies the French Hussy the way it should be flown by everyone and I'll bet you Swiss is doing the same.

 

[derg]

And to answer your question, many times V1 and Vr are equal for us.

Speaking of speeds, we had a 120kt Vapp into DTW a few days ago. It was like I was approaching a helipad in the wind. I damned near went back for a pre-arrival pee.

 

[PositionAndHold]

We are, and I edited my post to make what I was saying a bit more clear after you quoted it.

I just don't like the "it takes 5 knots to make a decision" thing when the time to go through that 5 knots can vary quite dramatically.

On all the transport jets that I've flown, we have the inhibit function above 80 knots, and say for an engine fire... it's not someone calling it out. It's immediate red lights and a bell. Your reaction to that is pretty stinking lighting fast.

Reacting to an engine flameout on the other hand is considerably slower since the engine slowly unspools. You'll first notice it in the yaw and then the generator changeover. Then the caution will finally light up. Hence my emphasis on the variance.

And to answer your question, many times V1 and Vr are equal for us.

That makes sense. As far as ours go it's the same. The 'ol Ding, Ding, Ding. We also rarely operate with an equal V1/Vr. Usually about a 5-6kts spread. Like @Derg said, it's an interesting discussion even after a bottle and a half of vino.

 

[derg]

That makes sense. As far as ours go it's the same. The 'ol Ding, Ding, Ding. We also rarely operate with an equal V1/Vr. Usually about a 5-6kts spread. Like @Derg said, it's an interesting discussion even after a bottle and a half of vino.

What kind of airplane?

 

[PeanuckleCRJ]

Speaking of speeds, we had a 120kt Vapp into DTW a few days ago. It was like I was approaching a helipad in the wind. I damned near went back for a pre-arrival pee.

Ha! I'm always manual thrust on approaches like that... it gets a bit gusty on that kite we call an airbus at that weight and the AT gets behind quick!

 

[PositionAndHold]

What kind of airplane?

Lear 45, not as cool as @SteveC shiny new Lear 75. I have flown the mighty ERJ-145 before the great XJT furlough of '07. More importantly, what kind of beer?