Low flying Apache not on ADS-B - why?

[_Mja_]

Hi,

Just curious really. Three times this week an Apache, pretty sure but definitely military, has flown over the land behind my house at very low altitudes off into the distance and then comes back again.

It's just been out again but there is no trace of it on ADS-B. I'm based near Duxford but in the hills in Hertfordshire - I can see down the upland areas out to the flats of cambridgeshire.

Just wondering what sort of reasons why it would be flying so low and assume that is why it doesn't show up on radar tracking. I guess it is training as I've seen it a few times now, obvious elephant in the room and training for that perhaps.

I see some chinnocks once a month that make the house shake but the are much higher than this Apache.

[_Mja_]

and they have just come back - 2 of them - barley higher than the roof of my house. Still no sign on flight trackers

[Caddyshack]

I think you have answered your own question. Training to be under radar.

[_Mja_]

interesting, cheers.

[Silver3ides]

These 2 ?

[_Mja_]

yes those are the ones and I live in one of the hamlets just before they appeared

[Equus]

There was one buggering about on the outskirts of King's Lynn yesterday afternoon too.

[Silver3ides]

_Mja_ said:

yes those are the ones and I live in one of the hamlets just before they appeared

Could be the transponders turned off for LL Training as said or no receivers feeding into the systems when really low in the area.

[Caddyshack]

Apart from very rare escorts such as when Trump visited the U.K. I don’t think any Apache flight is anything other than training?

Counter terrorism / SAS have an Apache standby, I think?

We sometimes see them near Bordon and I think that is RAF odiham training.

[Jakg]

_Mja_ said:

It's just been out again but there is no trace of it on ADS-B. I'm based near Duxford but in the hills in Hertfordshire - I can see down the upland areas out to the flats of cambridgeshire.

Equus said:

There was one buggering about on the outskirts of King's Lynn yesterday afternoon too.

I live near RAF Wattisham and Apaches are a regular sight - once a month at least.
I'd imagine thats where they are coming from
Always visible on ADS-B.

I think flying below radar is a likely explanation - while driving to work I've been in a valley* and seen them pop up from behind trees and line me up in the car practicing.

• I say valley, Suffolk is very flat...

[smack]

The trackers sights don't use radar, they rely on receiving stations picking up the signals sent from an aircraft, not transponders which responds to radio-frequency interrogation. The receivers more often than not Raspberry Pi's as they are cheap and don't use much power.
ADS-B stands form "Automatic Dependent Surveillance – Broadcast", which is the system that broadcasts information, about an aircraft's GPS location, altitude, ground speed. This is the system installed in all modern airliners, and increasingly small planes.

Here is some the messages being sent from an Atlas Air 747-400 flying to Ramstein Air Base, and happens to be an ex Virgin Atlantic aircraft Atlas picked up for US Government contract work to move troops.

The aircraft is broadcasting the hex code of a5ed66, with a callsign of GTI8088, flying at 35000 feet, 565 knots airspeed, and track/heading of 102 degrees, along with it's GPS position.

MSG,8,1,1,A5ED66,1,2022/02/16,00:18:10.319,2022/02/16,00:18:10.365,,,,,,,,,,,,0
MSG,3,1,1,A5ED66,1,2022/02/16,00:18:10.343,2022/02/16,00:18:10.367,,35000,,,51.64175,-1.15295,,,,,,0
MSG,5,1,1,A5ED66,1,2022/02/16,00:20:56.231,2022/02/16,00:20:56.280,GTI8088 ,35000,,,,,,,0,,0,
MSG,4,1,1,A5ED66,1,2022/02/16,00:21:37.084,2022/02/16,00:21:37.130,,,565,102,,,0,,,,,0

Most Military aircraft, older airliners (although most have been upgraded with ADS-B out systems), helicopters and some smaller aircraft, use Mode-S, which just broadcast hex and callsign information if they have it set. It doesn't send position data out, so requires multiple receivers to receive the broadcast information (minimum 3) , so it can be triangulated and the aircraft position worked on, known as MLAT or Multilateration.

So if there isn't enough coverage, receivers close to each other, they won't show up. I can pick up Apaches when flying out and about 5-8 miles away, but that depends on what is in the way of the helicopter and your receiving antenna. Western Military aircraft are going over to an encrypted system, so those with the encryption key can see the aircraft, such as friendly countries ATC systems, and those who you don't want to read the messages can't. Often if military aircraft are flying in formation, only one will be broadcasting, and I also occasionally see single UK Military helicopters fly past solo with their system turned off.

Nothing is flying at this hour close to me with Mode-S, so I can't see what they actually transmit, as I have never bothered to pay attention.

[Tony1963]

Caddyshack said:

Apart from very rare escorts such as when Trump visited the U.K. I don’t think any Apache flight is anything other than training?

Counter terrorism / SAS have an Apache standby, I think?

We sometimes see them near Bordon and I think that is RAF odiham training.

No, we don’t have an Apache on Standby for anyone. A handful are kept at readiness if possible, but training commitments override that.

This week, and maybe for a few weeks yet, there has been a lot of flying to Sculthorpe and then on to Holbeach for rocket and gun firing.

Edited by Tony1963 on Wednesday 16th February 18:19

[Caddyshack]

Tony1963 said:

Caddyshack said:

Apart from very rare escorts such as when Trump visited the U.K. I don’t think any Apache flight is anything other than training?

Counter terrorism / SAS have an Apache standby, I think?

We sometimes see them near Bordon and I think that is RAF odiham training.

No, we don’t have an Apache on Standby for anyone. A handful are kept at readiness if possible, but training commitments override that.

This week, and maybe for a few weeks yet, there has been a lot of flying to Sculthorpe and then on to Holbeach for rocket and gun firing.

Edited by Tony1963 on Wednesday 16th February 18:19

Thanks, I think when one of the London terror attacks went down there was an Apache that came in to support the SAS, would they have have put a call out and got lucky that there was one ready? I read in one of the Apache books from Afghanistan that it took 20-40 mins iirc…to do all pre-flight checks and flick of switches to take off…does that sound about right? I guess that would be fully bombed and fuelled up.

[Tony1963]

There are no Apaches on any form of Quick Reaction Alert, so yes, they’d need to take the (serviceable!) aircraft out of the hangar to the dispersal, arm it (maybe change its role to suit beforehand) go through the start procedure, then take off and fly from Wattisham (or Middle Wallop until a couple of years ago) to London. Not a quick process.

I’d guess that if there were heightened tensions a couple of Apaches could be detached to Northolt, kept armed and ready to go, but you really wouldn’t want to fire that 30mm in a U.K. city, and as for the rockets and Hellfire… noooooooo.

[towser44]

I would assume they can turn transponders off. I've seen it a few times over my house, when an Apache or 2 (or sometimes it is Chinooks or Merlins) flying over show on Global ADSB, but, when I pop outside to see them, there are more than the number showing on ADSB.

[Simpo Two]

Just thinking out loud - if you could track a/c by satellite (can you?), then radar would be obsolete.

[eccles]

Jakg said:

I live near RAF Wattisham and Apaches are a regular sight - once a month at least.
I'd imagine thats where they are coming from
Always visible on ADS-B.

I think flying below radar is a likely explanation - while driving to work I've been in a valley* and seen them pop up from behind trees and line me up in the car practicing.

• I say valley, Suffolk is very flat...

I love that you still call it RAF Wattisham even though they've been gone 30 years! I winds the Army up no end!

[TechBod]

eccles said:

I love that you still call it RAF Wattisham even though they've been gone 30 years! I winds the Army up no end!

Its because its still signed as RAF Wattisham... and is probably still classed as an RAF Base, the same as RAF Alconbury, American, RAF Lakenheath, American, etc etc.

Unless the base gets renamed xxxxxxx Baracks, it will retain the RAF base name.

[Tony1963]

No, it isn’t RAF Wattisham. It is usually referred to as either Wattisham Flying Station or Wattisham Airfield. There are only a small number of RAF personnel, all safety equipment fitters I think. Since Search and Rescue left, there has been no reason to make the mistake of calling it RAF Wattisham except that it’s a habit.

[Tony1963]

And it isn’t signposted as RAF either



That’s in Bildeston. Might be one or two signs that have been forgotten about, but they’re just wrong