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Qatari515
26th Sep 2008, 18:23
Flying in the Gulf for a major carrier (guess), I have been wondering about the following for many years.

In our SOP it is written that, flying in this military sensitive region, we should always keep the Wx radar on for military identification.

Nobody has been able to confirm the technical reason behind this to me so far, nor does anybody knows where this rule is coming from.
But, in true Gulf style, everybody blindly follows this rule, flying day in day out with WX radar on!

I have the strong feeling that this is a very old recommendation from before the TCAS era, which has been put in the SOP on which our SOP has been based many years ago. The rule hase become an urban myth and nobody has dared since, due to the lack of the necessary technical knowledge, to question it.

I know this practice was started when a jetliner was shot down over Chah Bahar in Iran by accident by the military. But technology has evolved a lot since than.

I can be wrong but dont the military pilots these days have better ways of identifying a civil airliner besides watching the returns of our WX radars.

Could anybody here, preferentially a military pilot, shed some light on this topic?

MAny thanks

uniuniunium
26th Sep 2008, 18:50
I'm by no means an expert here, but my understanding is that military radar receivers/processors are able to discriminate between different radar emissions based on band/frequency and therefore able to identify the radar set in use. This would allow the radar operator on the ground to verify that a target identifying itself as an airliner is not an impostor, since a military aircraft would not be equipped with a civilian WXR.

kijangnim
26th Sep 2008, 19:01
Greetings
This requirement was issued after US navy shoot down an Iran Air Civilian Airbus, over the Persian sea.
WX Radar has a Frequency, PRF etc fwhich form a signature enabling the military to identify the source and therefore to classify the source as being civilian.

galaxy flyer
27th Sep 2008, 00:42
It is a US NOTAM for operations in the Gulf. We did, even as a US Mil operation.

MIDDLE EAST AND EASTERN MEDITERRANEAN
KFDC A0029/03
SPECIAL NOTICE.
a. U.S. and allied military units (Coalition military forces) may operate throughout the Middle East and the airspace above the Eastern Mediterranean sea, Red Sea, Gulf of Aden, Arabian Sea, Gulf of Oman, and the Arabian Gulf. The timely and accurate identification of civil aircraft in these areas is critical to avoid the inadvertent use of force against civil aircraft. Coalition military forces are prepared to exercise self-defense measures, as may be necessary, to ensure their safety in the event they are approached by unidentified aircraft (fixed-wing, or helicopter).
b. In addition, the territorial airspace of Iraq is closed to all non-coalition aircraft, except Central Command authorized medical, firefighting, rescue/recovery and humanitarian flights, until further notice. Aircraft entering this airspace do so at their own risk. Coalition forces are prepared to respond decisively to any hostile acts or indications of hostile intent. This notice is also provided to ensure the safety of coalition forces and their facilities. All aircraft or flight activities that are determined to be threats to coalition forces may be subject to interception, quarantine, disabling or destruction. This includes aircraft within Iraqi territorial airspace and ground-based assets and activities throughout Iraq without regard to registry.
c. The timely and accurate identification of civil aircraft operating within these affected areas is essential to preclude the inadvertent use of military force against civil aircraft.
1. To better enable U.S. military forces to identify civil aircraft, all civil aircraft flying within or entering the affected area shall continuously monitor one or both international emergency frequencies (VHF 121.5 Mhz and/or UHF 243.0 Mhz UHF).
2. When an aircraft carries a serviceable transponder, the pilot shall operate the transponder at all times during the flight, regardless of whether the aircraft is within or outside airspace where SSR is used for ATS purposes. All crews are reminded to continuously operate the SSR transponder in accordance with the ICAO provisions (PANS-ATM-Chapter 8, PANS-OPS, Vol 1, Part VII and ICAO Doc 7030 Chapter 8).
3. When an aircraft carries serviceable weather radar, the pilot shall operate it at all times during the flight within the affected area, regardless of weather conditions.
4. The pilot should ensure continuous display of aircraft exterior and cabin lighting and illumination of logo light, if possible.
d. Unidentified aircraft and/or those whose intentions are unclear to U.S. and Coalition military forces will be contacted using the English language on VHF 121.5 Mhz and/or UHF 243.0 Mhz and requested to identify themselves and to state their intentions. Such contacts may originate from military surface and/or airborne units. U.S. radio communications will use standard phraselogy and will specify the aircraft's flight information, as available, to include: heading, Flight Level or altitude, SSR code squawk, geographical coordinates, and ground speed, civil aircraft receiving advisory calls shall acknowledge the message on the frequency on which the message was received and provide the information requested.
e. In the event an aircraft remains unidentified and/or is deemed to pose a threat to U.S. military forces, an emergency situation exists. In this circumstance, the pilots must be prepared to exercise their emergency authority to deviate from the ATC clearance as required: comply with recommended heading and/or altitude changes provided by U.S. military forces; and notify the appropriate ATC facility of the deviation and the need for an amended clearance.
f. Civil aircraft transiting the affected area outside published ATS routes are more susceptible to the procedures published herein. All aircraft are requested to avoid, as much as practical, abrupt and unusual changes of heading and/or altitude which may be construed as inconsistent with normal civil aircraft flight patterns.
NOTE-
This information is provided to warn all operators that U.S. and allied military forces are exercising self-defense measures. The measures will be implemented in a manner that does not unduly interfere with the right of overflight in international airspace. (AIA-100 11/24/03)

Qatari515
27th Sep 2008, 12:04
Thanks a lot guys, exactly what I was looking for.

Any idea when this notam was issued and what its validity was/is? I have never seen this one, which is strange as it clarifies the whole issue!

:ok:

ACMS
27th Sep 2008, 12:48
Sometimes you can see a thin spike or wedge on your radar through 1,2 or more sweeps. I'm told this is a Military radar jamming or interrogating your wx radar. I've seen it in the middle of the Pacific ocean for a few mintues, must have been the US Navy checking us out.

maybe someone else has the tech info on what exactly happens?

ACMS
27th Sep 2008, 12:52
Oops, just found this in my Honeywell RDR4000 manual.

EFFECTS OF INTERFERING RF SOURCES
An interfering radio frequency (RF) source operating at a frequency close to
the radar’s operating frequency can create unusual returns on the display
(see figure below). These returns will appear as a single wedge of radar
return that extends from very close range (< 5 nm) out to maximum range for
the selected range scale. The wedge will typically cover from 3 to 5 degrees
in azimuth and may, depending on the strength of the source, appear from
green to red. These returns are caused by Continuous Wave (CW) sources of
RF radiation.
CW RF sources that can cause this effect include:
• CW Military Radar
• Radar Jamming Equipment
• Satellite Uplink Equipment
Adjusting the manual gain may help alleviate the effect of the interfering
source but the effect will not completely disappear until the interfering source
is no longer in the radar’s field of view and that area of the memory has been
refreshed.

x213a
27th Sep 2008, 13:10
Spoke jamming should not occur as a result of being "interrogated". The only interrogation is via the IFF transponder 1010/1011. Radar signatures are able to be captured passively.

Flight profile, compliance with airlanes and mode 2 are the primary identifiers. The radar signature is then just correlated with available info.

PAR31
27th Sep 2008, 16:10
And what about Military forces using civilian aircraft:
Falcon-50/900 Airbus 319-310-330 DC10 L1011 DC9 B767?
The country where I come from the Air Force is using the same WX of a civilian AC.
I am still confused.:hmm:
Par31

wiggy
27th Sep 2008, 16:31
It's not so much about discriminating between an aircraft with military vs civilian paintscheme, it's about that radar and it's capability. Are any of the types you list going to be an immediate threat to the opposition?

wiggy
27th Sep 2008, 16:41
Yep, I think it's also know as co-channel interference. It's not so much deliberate jamming or deliberate interrogation, it's just RF energy from another source entering your radar system when it is "listening" for it's own return.

There seems to be a persistant source "jammer" for the 744 wx radar to the South of the Maastrict sector....never been able to find it's source but it's often there.

forget
27th Sep 2008, 19:48
Yep, I think it's also know as co-channel interference. It's not so much deliberate jamming or deliberate interrogation, it's just RF energy from another source entering your radar system when it is "listening" for it's own return.

I think you'll find it's just another Wx Radar being picked up by your receiver. Didn't they (the spikes) used to be called 'Rabbit Tracks'.

galaxy flyer
27th Sep 2008, 21:06
The date of issue is on the bottom of the quoted text. It is in the FAA International NOTAM site. I just goggled it, but was aware of its existence duet to ex-mil. Still there, still valid. Yes, using it only identifies you as an operator of wx radar, a more innocent transmission. A reaction to the IranAir shootdown in the '80s

GF

parabellum
27th Sep 2008, 21:53
In 1990, after Saddam invaded Kuwait, we, (GF), continued to make regular scheduled trips from Europe to the Gulf and vice versa and came over Syria, Jordan and Saudi Arabia. We would see the pencil wedges come up to us from SW Iraq and they would often stay with us until we were well into Saudi going East and we lost them over Turkey going West.

We liaised with both RAF and USAF in various places and they said it was the anti aircraft batteries locking onto us for practice but that speed, height, direction, schedule etc. would tell them we were no threat, it was more a show of force. After Jan 16th 1991 they all disappeared!

Dan Winterland
28th Sep 2008, 02:57
The Russian SA2 system uses a frequency close to that of WX RDR. When flying over countries that are equipped with the SA2, 'spokes' are quite common. They are locking you up - and they shouldn't be!

Rule3
28th Sep 2008, 03:38
Qatari515, didn't KFDC A0029/03 answer your question.:ugh::{

ACMS
28th Sep 2008, 04:05
Forget:.............might be another radar? maybe so.........I quoted what Honeywell said in THEIR book about the phenomenon above and I believe them.

x213a
28th Sep 2008, 06:32
It could be also a form of anaprop, especially in the gulf region. Or mutual interference from surface based nav radars suffering from ducting.

What freq do your weather radars operate on? I'm assuming India band. If so then I cannot see how any fire control radars would have any significant effect on the display. Unless they were actively "jammed".

I cannot think of any situation where a civ airliner would be "jammed" for practice reasons. The only time a lock-on would occur is if an investigate procedure was called and the fire control radars would be used in conjunction with the surveillance radars and 10/10 10/11 / and a few other recievers.

Caveat,

This is purely from a navy point of view.

mensaboy
28th Sep 2008, 08:06
I have worked for a couple of operators whose SOP's were to only utilize the radar when in the vicinity of TR's or convective activity.(or any time in doubt) I used to think this was reasonable. Perhaps it was to save the effective 'life' of the radar or a method to minimize radiation propagation, I don't know.

After several instances of almost entering or actually entering areas of non-forecast convective activity (no forwarning either), I concluded that I will always keep the radar on. I believe modern radar is much less prone to adverse radiation as well.

Aside from the obvious benefit of not being identified as a hostile threat by some military, I do not see a downside for keeping the radar on. It might save you some grief a few times in your career.

cwatters
28th Sep 2008, 08:36
Using electrical power will increase fuel burn very slightly (just as driving a car with your car headlights on does). As a percentage it will be very very small though.

trimotor
2nd Oct 2008, 17:52
It's correct that this goes back over 20 years - what the military don't want to see is the beam type and PRF of a weapons radar...automatic systems might shoot you..