radar damage prior to take off?

[olderairhead]

I am currently under line training and my training Captain has told me that weather radar should not be used prior to takeoff because the ground return could damage the radar antennae.

In all my years of flying I have never heard of this. Is he just pulling my leg or is this in fact a possibility?

I look forward to sensible replies.

[InSoMnIaC]

I suspect he is just pulling his own middle leg.

[NSEU]

Firing the radar into a building only a few meters away from the radome was not recommended on older radars. Even so, old radar systems will have been retrofitted with diodes to prevent large reflected signals damaging the receiver.

Newer radars? Not sure. Although the transmitted signal is much weaker, the receiver may be much more sensitive to compensate for this. However, I'm sure they are an improvement on the older receivers with regards to protection.

The tower radar will be much more powerful than aircraft radar and they haven't been told to turn theirs off on the ground ;)

[By George]

Modern radars with PWS (predictive Wind Shear) and TERRAIN functions need to have the WX 'ON' to work. Not much point in having all this 'Buck Rodgers' stuff if you sit there and turn it all off! (not to mention looking at the weather, especially at night).

[A37575]

my training Captain has told me that weather radar should not be used prior to takeoff because the ground return could damage the radar antennae.

He is wrong and needs to get up to date by reading more. This is a common affliction with check and training captains who are selected not for their up to date technical knowledge (far from it most of the time) but for their climb the greasy pole skills.

[By George]

Re-reading the original post I assume you mean that you'll turn it all on during line-up. In any case the power output these days is so low I only have it off during re-fuelling and at the gate. Quite often during taxi its a chance to scan the wx in the direction of departure. We get a lot of TS around here.

[PENKO]

Check your FCOM on weather radars. Read the limitations chapter. Read your OM B and A. Ask another trainer in your company. If still no reference to this supposed 'damage' then highly suspect the trainer of making up his own SOP.

More relevant to us: what type are you flying? My experience is limited to the 737 and 320, never heard of self inflicted radar damage.

[Piltdown Man]

Some aircraft are even fitted with override buttons to enable the crew to force it radiate on the ground. On really horrible days it is something, I like you, prefer to do in order to prevent 'surprises' when airborne.

PM

[Anthill]

Your 'Training' Captain is incorrect in this instance. No damage will result. Wx radar is designed to be used on the ground prior to take-off. It should not be referenced during the TO roll (otherwise damage may result to the antenne, radome, wings, gear etc as you crash of the side of the RWY.. :8).

As you get more exposure and experience in the industry you will be able to be more discerning regarding what you hear from some other pilots. My advise would be to get into the books and refer to the printed word and talk to the Chief Pilot. Increase your knowledge and develop an understanding of what you are doing. This will enable you to eventually make the transition from Co-Pilot to Captain as you gain more experience and understanding of SOPs and the equipment that you use.

Knowledge of SOPs is key to effective CRM, Note the Standard means a written standard, not what is 'usual' or what everybody else does. A practice may be unusual and yet still SOP. Effective CRM has 2 components: Safety and Efficiency. To arrive that these 2 goals, it is a requirement that you know your books. This ideal means that use must know when you can and can't use the wx radar and also extends into things like checklist use during non-normals. Another example: Think about your home port: what RWY/TWYs can you use/not use? if you cannot answer these simple operational questions, then you are a burden to your Captain and a CRM threat.

Lack of knowledge is a dangerous thing. :ok:

PS: Some modern radars do not even need to be switched ON for the PWS system to work. They use a "pop-up" system in a passive mode.

[BOAC]

A moment's pause - we do not know what sort of a/c type / radar we are talking about, do we? No clues from the OP. There are probably still some old high-power kits around where some damage can occur.

I would suggest some middle ground here?

1) Teach 'careful and selective' use of radar - use it only as required
2) Know your equipment

[rudderrudderrat]

Even with equipment built in 1960s (VC9 & 707s), we used the WX radar for take off. It was set with the tilt angle to +5 degs (so no close ground return) and so we could avoid any CBs on the initial climb out.

We could apparently damage the receivers if it was switched on whilst facing a hangar door or large building - but even those sets were designed to be used on take off.

Is any body still using stuff designed in the 50s?

[Maurice Chavez]

The old AVQ10's did get damaged if they were pointed to buildings, etc etc...

[ampclamp]

The original statement was "the ground return could damage the antenna" It appears many are talking about the actual radar tx/rx.

You will not damage the antenna unless mishandled or the radome hits something really hard:uhoh:.

Yes, modern radar tx/rx's are much less powerful as the rx's are indeed more sensitive.They are highly sophisticated and pretty much pilot and engineer proof in operation.
But many maintenance manuals do not allow operation whilst anywhere near a building / metal structures.Damage is unlikely but it is not allowed 'just in case' like many things in the industry. Such high frequencies are not good for people and should be avoided.

So your trainer is in essence incorrect.The WXR in general can be used (and are) on the ground given it is away from people, refueling and structures (distances differ so not quoted), ie lining up , throttles fwd etc.
It (the antenna) will not be damaged by ground returns.Their is a possibility of receiver damage if operated in close proximity to metal structures.There are electronic cct's that stop damage but why test it out unnecessarily?

[BOAC]

ampclamp - the early mil intercept radars could indeed be damaged by spill from the tx feeding back the ground return a few feet under the radome.

[Checkboard]

The Sensitivity Timing Control (http://www.radartutorial.eu/17.bauteile/bt22.en.html) (STC) on the radar adjusts the gain of the receiver so that returns from near objects don't overwhelm the set.

[mcdhu]

From A320 Series FCOM 3 Supp Techniques, Nav, Radar

[QUOTE]

Before selecting WX, WX/T or MAP mode on the control unit, make certain that :


No one is within a distance less than 5 meters from the antenna in movement, within an arc of plus or minus 135° on either side of the aircraft centerline.



The aircraft is not directed towards any large metallic obstacle, such as a hangar, which is within 5 meters in an arc of plus or minus 90° on either side of the aircraft centerline.

/QUOTE]

mcdhu

[Pontius Navigator]

One reason for not emitting on the ground was indeed the Radhaz to people rather than powerful returns. The other reason is not so much for self-damage as damage to other radar sets. A set powered off has not protection circuits activated but could be subjected to high powered emission that might cause damage. It was for that reason we used to set our antenna to the 180 degree position before powering down.

[Pub User]

Some weather radars will activate when the thrust levers are advanced, in order to enable the Predictive Windshear function, even when they are not switched on.

[ampclamp]

Hi boac,
That is interesting.I am sure those were very high power rigs but to do actual damage to the dish (presumably a dish in those days) would be quite something.
Anyway that is certainly not an issue today as presented by the original poster.

question to oldairhead: what type of aircraft are you flying?

[BOAC]

question to oldairhead: what type of aircraft are you flying? - indeed -as I said - that would help!

The 'damage' was to the receiver circuit, not the antenna.

[ampclamp]

Thanks BOAC.
Thats what I was getting at earlier.My response was always about the original statement (how often does that get lost here !??) that his training skipper says it can damage the antenna.

[BOAC]

ampclamp - I would not put too much store on precise wording.

[ampclamp]

Yes that is fair enough but if his trainer said exactly that it's bollocks and he needs to know why.

So often here we get questions asked with dozens of answers showing how much posters know but still leave the question un-answered.

I have noticed you are one of the better ones around and appreciate the input.
Now, if we knew what he/she was flying and the wxr install is.....:confused:

[BOAC]

'Flutters eyelids'.........................well, one does try.

This is fairly typical of this (and indeed any) forum -

OP fires in question with 'holes' in it.
The masses argue about it and often go off on complete tangents
OP 'disappears' and we are left with a three page thread and no answer.

Still, it all can be educational:)

[Pontius Navigator]

BOAC, agree. The old aerial is simply a reflector and collector with only mechanical parts. It is possible that newer aerials incorporate some protection devices but not that I have heard of.

Now the 2 Mw emitters I last flew with would do a fair job of frying anything at short range :}