Same everything, but slower…

Can’t seem to figure this one out. While conducting a flight with a group of four, following the same flight path, the same altitude, and the same cruise speed (.84) my GS is consistently showing 6-8kts slower in GS. One aircraft is different, so let’s call it a flight of 3, and I’m the trail aircraft. The vertical separation has steadily increased from an initial distance of 11/12nm to 28nm. As I said we’re at the same altitude, same aircraft, same cruise, and just for additional info I’m lighter at 58% vs 69%. The speed on the AP and HUD are matching as well, this isn’t a situation where the AP says .84 but the HUD says .83.

Similar issues were found in a search, but they seemed to have minor differences in altitude, etc that aren’t present here.

The speed depends on the altitude you are flying, even if the other aircraft is close to you, the difference of the AGL causes some difference in GS of about 5-6kts, the speed difference might maybe be caused due to the difference of mass of the aircraft

If we’re on the same flight path though, shouldn’t it even out as I would pass over the same terrain and have the same AGL profile? I know the speeds won’t consistently match, and there will be discrepancies in the speeds displayed. However, shouldn’t this also mean that when the cause of the displayed speed increase of the lead aircraft goes away, I should at some point show a speed greater than them? They’ve flown through whatever affected them, while I still haven’t reached that point since I’m trailing.

Even if it’s on the same path, you are going really fast and the terrain changes really rapidly, even if you are at say 3nm.

The most probable thing here would be the tailwind/headwind component. Winds change which will affect your flight in the long run. Best bet would be monitor if you can and adjust speed if you see these differences in your GS(ground speed) not your IAS(indicated air speed).

This is because your indicated airspeed May both be 273IAS, one may be at 540 GS and you may be at 543 GS which over a long stretch of time will cause separation to change. This is due to a tailwind or headwind component. Your GS will increase with a tailwind but your IAS will most likely remain the same.

Most likely the tailwinds here were stronger for the person ahead and hence they were able to build a lead

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Correct, but the flight path would carry us over the same terrain, right? So the same fluctuations will eventually be encountered by each plane on the same patch. If this was not the case, then why does the separation not increase between the other members of the flight and they show a GS of +/-1 of each other. The terrain theory would impact each aircraft, not just 1.

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remember this is a game and so connections might have a play, i have flown a flight a few time with others and our winds can be different though out the flight by a few degrees and kts and so this will cause both of us to have different speeds. so for example i could have wind at 350 degrees at 25kts and my buddy could have 345 dgrees at 23kts and we would have different ground speeds. IF isnt perfect and nor is devices or internet so things may differ between people

There are no similar flights, there are always several factors that influence, mainly the winds

I agree that they would build a lead if those conditions were encountered. However, it’s an ever expanding gap that has elapsed 2+ hours.

Thanks, at this point I think something along those lines seems most plausible. I appreciate it

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Thanks to all who responded. I appreciate the feedback.

A little point I’d like to add : at cruise alt and speed, 1°C less will increase GS by1kt or 2, both in IF and RL.

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