B747-400 Patch Above Door 4

[236 Series]

Strange one this. Can anyone inform me what the noticeable patch on the B747-400 fuselage skin is above door 4.

Noticed this on BA B747-400's and Lufthansa ones aswell. Looks like a repair scheme of sorts but why?

[MaxDiff]

Satcom Antenna.

[236 Series]

I'm still confused. I thought Satcom antenna were located on the top of the fauselage. The patch I'm referring to is literally above door 4, more or less flush to the aircraft skin, measuring roughly 24 bu 24 inches. I only noticed this anomaly when the old paint schemes on BA's B747/4's became washed out!

[MaxDiff]

As previously stated.
S.M.H.G.A
Side Mounted High Gain Antenna.
Yes, it's located slightly fwd & above door's 4 L/R & is basically flush flat & square etc.

[getitright]

could it be they are gps flat plate antennae?

[MaxDiff]

Dear GETITRIGHT,

For the last and final time SATCOM SATCOM SATCOM !!

The GPS Antenna are approx 3" x 5" & not visible from the ground as they are located on the roof of the A/C roughly in line with the wing L/E.

If you still won't believe me check out B744 MM 23-25-00.

Cheers Max.

[QAVION]

"For the last and final time SATCOM SATCOM SATCOM !!"

It's a hard crowd here, isn't it Max ! :-)

For the disbelievers...

If the 400 Satcom has a dual antennae installation, then this is the most likely place for them. These antennae are fairly thin and would suggest a patch. A single antenna system has a top mounted antenna and can be quite bulky.
Satcom ops manuals suggest that the side mounted antennae should not be used when door 4L/4R are in use.

GPS antennae are about the size of your average computer mouse (only flatter).

Rgds.
Qavion.

[MaxDiff]

Three cheers for QAVION !!

Thank's mate BRGDS Max.

[moremj2]

Can anyone help identify the small fin (LHS I think) at 1/2 distance Vert stab, again on -400. Ive rarely seen it long enough to identify. Thanks in advance...

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If you're going out into the blue, be sure your engines got more mj2

[236 Series]

Thanks to Max Diff in taking the time out in answering my question. The fog has lifted!

[spannersatcx]

moremj2, on our 400's it is a BBC antenna, so you can listen to the world service, don't ask me who listens to it as the reception is crap