ILS failing during approach

pclancy

If you were flying IMC down an ILS, how would you know that the signal is accurate and you're not being misguided by faulty or badly calibrated vertical or horizontal indications or that the autopilot is happily following an incorrect approach path? Especially in an unfamilar aiport.

Are you constantly checking heights and DME readouts compared to fixes on the approach plate?

Just something popped into my head watching planes land in bad weather.

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Your approach plate will give you some DME distances and associated heights. Like at the outer marker or passing beacons.

You can also use your DME reading to calculate what your height should be at any point on the GS.

For example most glideslopes are at 3 degrees. If the DME reading is from the threshold then just multiply your DME distance by three to give your height.
i.e. 7 nm out, then 2100 feet.

Your position in relation to the locator can be verified by using a radial from a VOR or NDB. This acts as a good back up.
One should always identify the navaids used for the approach. In training we did this before commencement of the approach and then again (time permitting) once localiser established.

Modern aircraft can auto-identify however and the particular navigation aids code is displayed on the ND letting the pilot know its working.

Your nav instruments have failure flags on them also letting you know of possible problems.

ATC will also be aware of your position and bollock you if you fly too wide or low.

highlydebased

An example of the check heights on this plate...(red box)

drdeadlift

Not really ontopic havent seen an updated jepp chart for dub but is there a new vor located at the end of runway 10 ?

highlydebased

drdeadlift wrote: »

Not really ontopic havent seen an updated jepp chart for dub but is there a new vor located at the end of runway 10 ?

Yes DAP is...it just not on the 28 chart

drdeadlift

Neon-Circles wrote: »

Yes DAP is...it just not on the 28 chart

Ah cool,i seen it the other day when passing the airport.Is the original still in use? silly question what was the need for the new vor??

diverdriver

DAP is a terminal VOR. It's short range only and as such it's used for VOR approaches to 28 or 10. So the need for it is in fact when the ILS fails. It's a back up approach. DUB VOR could be used too but the minimums would be higher because it's more closely aligned with 16/34.

drdeadlift

diverdriver wrote: »

DAP is a terminal VOR. It's short range only and as such it's used for VOR approaches to 28 or 10. So the need for it is in fact when the ILS fails. It's a back up approach. DUB VOR could be used too but the minimums would be higher because it's more closely aligned with 16/34.

Spot on man,cheers for the info!

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Neon-circles is there somewhere online where you can get jpegs of these jepp charts?

I've been wanting to get all EIDW's charts but without paying full whack!

diverdriver

You could use the official IAA approach plates in the AIP online!

highlydebased

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Neon-circles is there somewhere online where you can get jpegs of these jepp charts?

I've been wanting to get all EIDW's charts but without paying full whack!

Send me a PM and I can sort you out.....if not just use the IAA ones