Guys.  Please no Internet drama, on my behalf or otherwise.  LRBS and I have both been airline captains and check airmen for many years.  We're peers.  This isn't one of us lecturing or teaching the other.  It's just a discussion, the same as I would have with another instructor over a beer.  It's fun to get into the weeds on this kind of stuff, that's all.  I see this particular issue as more of a human factors / risk mitigation exploration, vs a technical issue.  That's probably not fun for everyone, but I like it. 😉. Other instructors usually do too, which is why it being perceived as some kind of attack confused me.  I think there was some misunderstanding, hopefully all better now.

On 3/17/2026 at 11:32 AM, LRBS said:

This clarifies everything:" You can't really perform a verification unless you're comparing data from different sources.   ''  That's the key point, yes, we do. Most airlines, here in the States or abroad, will provide the information I was referring to in the performance data printout.

Ok, so this is interesting.  Where does the runway margin data come from, if it's not included by your performance calculator in a perf solution?

For fun, I reached out to a couple buddies who fly for two other US legacy airlines, and asked them for examples of their takeoff data reports.  They both use the Aerodata cloud calculation system, so of course they are pretty similar.  I won't post either of those here, but here's an identical Aerodata takeoff performance report I found online (it's obviously for a corporate jet, but all the same data is provided - and omitted).

https://www.garmin.com/en-US/blog/wp-content/uploads/2020/12/2-GP-P-FPc-NavLog-TLR-calc-top-copy-1136x1536.jpg

We use a different tool called DynamicSource that does the same thing - server-side calculations of perf solutions based on parameters we specify (or optimum by default).  Our reports contain exactly the same data, the only extra field being a customized obstacle clearance height that is used in our takeoff profile (it's just an altitude you maintain clean maneuver speed until passing if engine-out).  

So that's at least three US legacy airlines that aren't directly reviewing runway margin data as part of a takeoff performance solution, because it's built in.  (Most regionals are now using one or the other of these systems as well).

I'm not criticizing anyone for using a different system or different techniques, it's just always fun to see how folks are doing things at different properties.  It seems there may have been some perception that directly reviewing runway margin data is an industry-standard part of takeoff data review, and as you can see, it really isn't.  That doesn't mean there aren't places doing it, but it does call into question what purpose is really being served by doing so.  That's the discussion I was looking for; I'd like to understand that position.

1 hour ago, Stearmandriver said:

Guys.  Please no Internet drama, on my behalf or otherwise.  LRBS and I have both been airline captains and check airmen for many years.  We're peers.  This isn't one of us lecturing or teaching the other.  It's just a discussion, the same as I would have with another instructor over a beer.  It's fun to get into the weeds on this kind of stuff, that's all.  I see this particular issue as more of a human factors / risk mitigation exploration, vs a technical issue.  That's probably not fun for everyone, but I like it. 😉. Other instructors usually do too, which is why it being perceived as some kind of attack confused me.  I think there was some misunderstanding, hopefully all better now.

Ok, so this is interesting.  Where does the runway margin data come from, if it's not included by your performance calculator in a perf solution?

For fun, I reached out to a couple buddies who fly for two other US legacy airlines, and asked them for examples of their takeoff data reports.  They both use the Aerodata cloud calculation system, so of course they are pretty similar.  I won't post either of those here, but here's an identical Aerodata takeoff performance report I found online (it's obviously for a corporate jet, but all the same data is provided - and omitted).

https://www.garmin.com/en-US/blog/wp-content/uploads/2020/12/2-GP-P-FPc-NavLog-TLR-calc-top-copy-1136x1536.jpg

We use a different tool called DynamicSource that does the same thing - server-side calculations of perf solutions based on parameters we specify (or optimum by default).  Our reports contain exactly the same data, the only extra field being a customized obstacle clearance height that is used in our takeoff profile (it's just an altitude you maintain clean maneuver speed until passing if engine-out).  

So that's at least three US legacy airlines that aren't directly reviewing runway margin data as part of a takeoff performance solution, because it's built in.  (Most regionals are now using one or the other of these systems as well).

I'm not criticizing anyone for using a different system or different techniques, it's just always fun to see how folks are doing things at different properties.  It seems there may have been some perception that directly reviewing runway margin data is an industry-standard part of takeoff data review, and as you can see, it really isn't.  That doesn't mean there aren't places doing it, but it does call into question what purpose is really being served by doing so.  That's the discussion I was looking for; I'd like to understand that position.

As @Stearmandriver mentioned, we just share information. 

For sure, each airline has different SOPs, and sometimes what others do might be completely different.

Obviously, this was a misunderstanding or a mistake on my part, and the key sentence was "comparing data."

I was involved with 5 careers doing type rides. All airlines use estimated weights for passengers (males, females, and children during summer and winter). The same applies to carry-on and certain bags, while suitcases and other bulk items are separated and weighed.  For military operations, we also use different data. For freight operations is actually more critical.

Here is the reason I mentioned those distances and concerns. Based on these weight estimates, the 5 US airlines and others outside the USA will inform the crew and offer the option to choose a different take-off rating when the stop margin is 500 FT or less. All of this is based on incidents or accidents in which mistakes were made. Perhaps for some airlines, operating shorter segments is not a concern; I don't know. 

I really hope this clarifies our discussion; no disrespect intended. As for "teaching", I have to admit I keep learning all the time despite my flight hours and years of service.

Edited March 19Mar 19 by LRBS

And  @Stearmandriver I forgot to mention: some airlines call V1 at 5 KTS prior to, and the PIC takes off the hands from the throttles. They say that, based on the data and statistics, it is prudent to do so and eliminate potential problems. Another example: we can elaborate on and disagree with. I've seen so many SOPs where the "sky is the limit." 

Here's the last one: some airlines have an SOP that, if 3,000 ft of runway remains and the aircraft hasn't yet reached Vr, they firewall the throttles. Apparently, verifying takeoff data and changing it during preflight is controversial. Such is life. 

 

Edited March 19Mar 19 by LRBS

Hm, I'm not convinced calling V1 5 knost earlier than calculated. 

Reaction has to be initialted before reaching it so lowering the call reduces the window in which you are legally still allowed to call abort. I would not want that window be smaller than it has to be.

Edited March 19Mar 19 by Farlis

9 minutes ago, Farlis said:

Hm, I'm not convinced calling V1 5 knost earlier than calculated. 

Recection has to be initialted before reaching it so lowering the call reduces the window in which you are legally still allowed to call abort. I would not want that window be smaller than it has to be.

Based on the data, it is more restrictive and safer than hesitating during or past V1.

Hey, I'm the messenger, don't shoot.

Regardless of our views, these SOPs are approved and in effect. I just shared with you guys what is out there.

Edited March 19Mar 19 by LRBS

Well if they say so. 

Coincidentaly some performance calculators give a V1 range (the Toliss one simulates this feature) under certain conditions. So the pilots themselves can decide if they want to go for a higher or a lower figure.

Not gonna waste my time watching someone's reposted YT video here on AvSim again!

From the screen shot alone all I can say is it looks like an Apple Ipad!!! What a toy.

 

8 minutes ago, Farlis said:

Well if they say so. 

Coincidentaly some performance calculators give a V1 range (the Toliss one simulates this feature) under certain conditions. So the pilots themselves can decide if they want to go for a higher or a lower figure.

Again, as a messenger, some operators call it exactly at V1, while others (including some Boeing-recommended procedures) suggest a 3-5-knot early call. It's often specified in the airline's Standard Operating Procedures (SOPs) or Flight Operations Manual. I have nothing to do with it, just sharing data. What we strongly believe, others do it differently. That's the reason we need to keep an open mind, regardless of our feelings. Years ago, I used to argue: when I was exposed to different airlines' environments and procedures, I learned the lesson. 

I can kind of see why. If you anticipate the call this way you will have reached V1 exactly as the words exit your mouth. If you say it AT V1 you are already above it when you finished saying "One".

Returning to this one late, but glad to see we're pretty well in agreement.  I'll correct one thing:

On 3/19/2026 at 8:15 AM, LRBS said:

Apparently, verifying takeoff data and changing it during preflight is controversial.

We request new takeoff data using different parameters all the time, as judgement dictates.  Didn't want to leave the impression that some airlines aren't doing that.  Certainly we also have a rigid procedure for verifying that the takeoff data solution is valid.  I assume every airline does.  It was only specifically the review of margin that I'm pointing out many airlines don't do.  I wouldn't call it "controversial", just one of those differences, as you say.  I've never heard the reason why margin is excluded but I could make some educated guesses from my time in human factors working groups, but I guess it doesn't really matter.

On 3/19/2026 at 2:15 PM, Farlis said:

I can kind of see why. If you anticipate the call this way you will have reached V1 exactly as the words exit your mouth. If you say it AT V1 you are already above it when you finished saying "One".

Pretty much.  This is something we do.  A takeoff data solution guarantees that you can stop if the RTO is initiated at V1, but not necessarily 1 knot above it.  Things are happening pretty quickly around V1, so if you use the actual V1 as the decision speed and you recognize a failure right at V1, you won't be initiating the abort until some speed above V1.  Calling V1 5kts early allows for recognition and reaction time and ensures an RTO isn't initiated above V1.  There are a lot of overrun accidents that were caused by a late abort.

Hi... But this is still fiction, not virtual reality. As someone wrote above: 'The nail in the coffin for PMDG,' etc. ... There is no SP1, so there is no nail. And soon it will be a year that we've been waiting for SP1... Maybe someday... who knows...

Yeah, that's another one for the list of kind of marketing I don't like. Teasing new features way in advance and then having to wait months, sometimes a year until release.

I keep repeating it in the vain hope developers will listen: Just shut up about your pipelines, work quietly and then do a week of video teasers like FSREBORN just did for their Phenom300 and then release after the week is over.

No drawn out anticipation over half a year with no idea how long it will take.

Hoping for an improved flight model, too.

After SP1, the next thing on the agenda is the FS2024 native model along with the MAX-9. At this rate, we'll all be on FS2028 by the time that sees the light of day! 🤣

iFly have always been deadly slow with progress, updates and developments. You get the feeling it's 3 guys, working on the plane 1 day a month, in between their real jobs, family commitments and other activities.

I agree with Farlis that they shouldn't have generated all that energy a few months ago, in teasing SP1 / the new EFB, when it's clearly not imminent.