Interesting aircraft - what have you seen on your computer today?
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?
Gnome de PPRuNe
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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...
Heard a familiar drone earlier this morning, one of the Ukrainian AN-26s outta Brum...
Originally Posted by treadigraph
G-ISMC doing circuits at Stapleford? Speed and height reports via ADS-B can be rather wayward
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.
Gnome de PPRuNe
Thread Starter
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?
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?
Originally Posted by treadigraph
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?
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?
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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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...
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...
Originally Posted by Duchess_Driver
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...
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...
Gnome de PPRuNe
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Originally Posted by DaveReidUK
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.
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.
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...
Originally Posted by treadigraph
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.
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 08:02.
Gnome de PPRuNe
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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.
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!
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.
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Originally Posted by treadigraph
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!
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!
Gnome de PPRuNe
Thread Starter
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'.
