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Interesting aircraft - what have you seen on your computer today?

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Interesting aircraft - what have you seen on your computer today?

Old 7th Jan 2021, 09:57
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This morning, I am rather intrigued by the only airborne light aircraft I can find, at least in the south. It has been wandering around Epping and Loughton at about 1000' at an astonishing speed reported as between 200 and 459 knots. According to GINFO he is out of Stapleford. Possibly weather related?
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Old 7th Jan 2021, 10:57
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G-ISMC doing circuits at Stapleford? Speed and height reports via ADS-B can be rather wayward, I've seen a Tiger Moth floating about Hampshire apparently at 60,000'!

Heard a familiar drone earlier this morning, one of the Ukrainian AN-26s outta Brum...
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Old 7th Jan 2021, 10:58
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Another of the BA 777's floated by in the freezing grey earlier this morning on delivery from Seattle into LHR and an AN-26 droned over heading Eastwards.
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Old 7th Jan 2021, 11:43
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Great minds post alike, SHJ...
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Old 7th Jan 2021, 13:25
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Originally Posted by treadigraph View Post
G-ISMC doing circuits at Stapleford? Speed and height reports via ADS-B can be rather wayward
ADS-B is usually pretty reliable. Unfortunately G-ISMC doesn't have it fitted - that's the problem.

In such cases, FR24 relies on multilateration, which is dodgy at the best of times. For example FR24 reckons the C152 has made several visits to LCY today, which sounds a tad unlikely.
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Old 7th Jan 2021, 14:05
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Ah, OK, I don't usually note whether its ADSB or MLAT...

Saw a relatively new French registered helicopter flying over here several times under low clag last year and reporting an altitude of 1000' - the land rises to 574' ASL locally and I saw it come right over the top of me on one occasion as I crossed that summit - it was very low, 300 - 400' sounds about right. Now my understanding is that F/W aircraft should be no less than 1000' over a built up area and helicopters 900' - can I presume that figure should be AGL and ADSB would be reporting ASL?
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Old 7th Jan 2021, 14:22
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Don't know if it's a Freedar glitch but has anyone else seen the alien UFO at 6000ft over Novya Zemlya in the Soviet Arctic?
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Old 7th Jan 2021, 16:30
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Originally Posted by treadigraph View Post
Ah, OK, I don't usually note whether its ADSB or MLAT...

Saw a relatively new French registered helicopter flying over here several times under low clag last year and reporting an altitude of 1000' - the land rises to 574' ASL locally and I saw it come right over the top of me on one occasion as I crossed that summit - it was very low, 300 - 400' sounds about right. Now my understanding is that F/W aircraft should be no less than 1000' over a built up area and helicopters 900' - can I presume that figure should be AGL and ADSB would be reporting ASL?
It's more complicated than that.

ADS-B reports altitude the same way as Flight Levels are derived - that's to say, based on a nominal QNH of 1013.2 mb (or hPa). So to work out actual height AMSL you need to adjust for the local QNH, and then if you want height AGL you need to factor in the terrain.
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Old 7th Jan 2021, 17:43
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Seems to me that there are many more “irregularities” with FR/Plane Finder/Flightaware at the moment.

Not too many days ago Emirates ran one of their Cirrus SR22s out of Heathrow direct DXB. It’s currently at 41K routing AMM to DXB. Hmmm...
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Old 7th Jan 2021, 18:14
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Originally Posted by Duchess_Driver View Post
Seems to me that there are many more “irregularities” with FR/Plane Finder/Flightaware at the moment.

Not too many days ago Emirates ran one of their Cirrus SR22s out of Heathrow direct DXB. It’s currently at 41K routing AMM to DXB. Hmmm...
You can hardly blame FR24 for the inability of Emirates/Airbus to configure a transponder correctly.
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Old 7th Jan 2021, 18:32
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Wasn’t blaming anybody, Dave, merely pointing out that the systems are GIGO and cannot be relied upon.
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Old 8th Jan 2021, 14:21
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A400 Atlas at Edinburgh for a couple of circuits this afternoon
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Old 8th Jan 2021, 15:28
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Comet 457, just went around at Newcastle
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Old 8th Jan 2021, 18:40
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Originally Posted by DaveReidUK View Post
It's more complicated than that.

ADS-B reports altitude the same way as Flight Levels are derived - that's to say, based on a nominal QNH of 1013.2 mb (or hPa). So to work out actual height AMSL you need to adjust for the local QNH, and then if you want height AGL you need to factor in the terrain.
But if this helicopter was at 400' AGL, should he not be at, say 1500' ASL to meet the regs? Most of the other helicopters and light aircraft I see are visibly at a sensible height (I've seen a couple of other aircraft which appear to have been way below 1000' and the area definitely conforms to "built up" though close to the edges) - and this guy was low.

In other news - two KC-10s have flown all the way up from Crete, made a sharp left just off Dungeness and are now heading west down the South Coast - approaching Portland as I type...
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Old 8th Jan 2021, 20:23
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Originally Posted by treadigraph View Post
But if this helicopter was at 400' AGL, should he not be at, say 1500' ASL to meet the regs? Most of the other helicopters and light aircraft I see are visibly at a sensible height (I've seen a couple of other aircraft which appear to have been way below 1000' and the area definitely conforms to "built up" though close to the edges) - and this guy was low.
Not having been there, I can't comment on what height the guy was flying at. I'm simply trying to explain why, most of the time, height reported by ADS-B will be higher or lower than the true height.

Edit: Had it been a recent event, we could have looked up the local QNH and applied that to get a reasonably accurate height AMSL, but I don't know of any online METAR source that goes back more than 5 days.

Last edited by DaveReidUK; 9th Jan 2021 at 09:02.
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Old 9th Jan 2021, 12:15
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I couldn't tell you when it was Dave, two occasions in the last six months. The first time he was about a mile west of me, the second right overhead and as I say, certainly well under 1000'. On the first occasion Biggin seemed to be below decision height as several bizjets had flown go arounds and were holding over Kent and one, a PC-24, passed over me unseen in the clag while diverting to Farnborough. I was just curious...

Just found the regs which say AGL which suggests he was certainly too low - the only helicopters I've seen as low as this was are the police (who mostly stay higher) and the air ambulances.
Except with the written permission of the CAA, an aircraft flying over a congested area of a city town or settlement shall not fly below a height of 1,000 feet above the highest fixed obstacle within a horizontal radius of 600 metres of the aircraft.
The French have history over here - about 35 years ago a French MS.500 flew over the common at about 500'! Very easily read off the reg with the naked eye!
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Old 9th Jan 2021, 17:07
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Originally Posted by treadigraph View Post
I couldn't tell you when it was Dave, two occasions in the last six months. The first time he was about a mile west of me, the second right overhead and as I say, certainly well under 1000'. On the first occasion Biggin seemed to be below decision height as several bizjets had flown go arounds and were holding over Kent and one, a PC-24, passed over me unseen in the clag while diverting to Farnborough. I was just curious...

Just found the regs which say AGL which suggests he was certainly too low - the only helicopters I've seen as low as this was are the police (who mostly stay higher) and the air ambulances.


The French have history over here - about 35 years ago a French MS.500 flew over the common at about 500'! Very easily read off the reg with the naked eye!
What's the definition of a congested area?
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Old 9th Jan 2021, 18:12
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A congested area means, 'in relation to a city, town or settlement, any area which is substantially used for residential, commercial, industrial or recreational purposes'.
Which defines the Croydon area without any doubt...
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Old 11th Jan 2021, 12:34
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Two Italian Air Force B767s flew westbound across the NAT over Jersey just after 11.00z this morning. Are these in flight refuelling or transport - or both ?
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Old 11th Jan 2021, 13:25
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They're KC-767s.
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