DME DISTANCE ON ILS

[ABE 0]

Sometimes when I am on final using the ILS, I do NOT get a reading of the distance to the runway displayed.Appreciate any help.Thanks.Abe

[mgh 89]

Sometimes when I am on final using the ILS, I do NOT get a reading of the distance to the runway displayed.Appreciate any help.Thanks.Abe

Not all ILS installations have DME.

[AWACS 12]

The FAF is usually 7 miles out, or when you're at the altitude you're supposed to maintain until established and then when the glideslope centers is usually the same as the FAF, from there you don't really need to know the distance just follow your glideslope to minimums and if you can see the runway lights you're usually in pretty good shape for a safe landing. Of course I'm sure someone will jump in here and correct me, I'm not instrument rated just yet.Jeff

[JET 1 0]

The FAF is usually 7 miles out, or when you're at the altitude you're supposed to maintain until established and then when the glideslope centers is usually the same as the FAF, from there you don't really need to know the distance just follow your glideslope to minimums and if you can see the runway lights you're usually in pretty good shape for a safe landing. Of course I'm sure someone will jump in here and correct me, I'm not instrument rated just yet.

Basically correct, an ILS does not NEED a DME. It may be required if the ILS approach procedure in question has stepdowns or other procedures based on distance prior to glideslope interception. It may also be used for height checks on the glideslope or to define a MAP if the glideslope goes out and the approach may be continued as a localiser approach.For the original poster, the simple answer is again, not all ILS systems have DME.

[Lmaire 38]

Sometime, you can use the VOR/DME, i mean nav 1 on ILS frequency and nav 2 on the vor frequency. But you have to make sure to know where the VOR is located. Examplethe threshold can be located 0,9nm from the VOR you have then to substract that distance from the indicated distance on the DME. Hope you understand. Sorry for my bad english. Lmaire

[threelittlefish 0]

Sometime, you can use the VOR/DME, i mean nav 1 on ILS frequency and nav 2 on the vor frequency. But you have to make sure to know where the VOR is located. Examplethe threshold can be located 0,9nm from the VOR you have then to substract that distance from the indicated distance on the DME. Hope you understand. Sorry for my bad english. Lmaire

This is not an acceptable practice. There is no need for a DME colocated on an ILS unless as previously stated the approach. The outer marker, middle marker and inner marker should be used to determine where you are on the ILS approach along with altitude. If a DME is colocated wit han ILS then the marker beacons are not required.

[scott967 62]

Even if there is a DME it generally is not at the threshold.scott s..

[ABE 0]

Even if there is a DME it generally is not at the threshold.scott s..

Thanks guys. Appreciate all the info.I realize that knowing the distance is not terribly important, but sure is NICE.....an added piece of information.Abe

[threelittlefish 0]

When on glideslope and localiser you shouldn't be looking at DME. Remember that your dealing with decision height and not a missed approach point as the point at which you go around or commit to landing.. Evne if DME is given as a MAP it is for use when the glideslope is inop and its a non precision localiser approach. Once you intercept the glideslope eliminate the DME from your scan.

[JET 1 0]

Once you intercept the glideslope eliminate the DME from your scan.

I disagree with that. You should use all information that is available to maintain situational awareness, which includes DME, especially if published height check points are based on DME. You could have false glideslope indications and that will give them away.

[threelittlefish 0]

I disagree with that. You should use all information that is available to maintain situational awareness, which includes DME, especially if published height check points are based on DME. You could have false glideslope indications and that will give them away.

Disagree if you wish but DME info is not given inside the FAF for an ILS approach. DME info only appears inside the FAF on an ILS approach plate if the ILS approach also serves as a localiser approach and is then provided to mark the MAP.Inside the FAF doing 150kts flying a manual approach in IMC there is no time or reason to include the DME in your scan. Inside the FAF the only thing I am interested in in the localizer/glideslope my airspeed/power setting, glideslope localiser flags, and marker beacons if applicable while the NFP is looking for the runway and backing me up on the instrument scan.

[JET 1 0]

Disagree if you wish but DME info is not given inside the FAF for an ILS approach. DME info only appears inside the FAF on an ILS approach plate if the ILS approach also serves as a localiser approach and is then provided to mark the MAP.Inside the FAF doing 150kts flying a manual approach in IMC there is no time or reason to include the DME in your scan. Inside the FAF the only thing I am interested in in the localizer/glideslope my airspeed/power setting, glideslope localiser flags, and marker beacons if applicable while the NFP is looking for the runway and backing me up on the instrument scan.

Point taken, and I'd love to agree with you, but you're wrong.One little thing first, ILS approaches don't have FAFs, they have FAPs. Only non-precision approaches have FAFs.And then, check this plate as an examplehttps://ais.fi/ais/eaip/aipcharts/efhk/hk22Lilscat2.pdfit's CAT II ILS only approach (not a LOC app, GS is required). Note DME required and and the height check points along the glidepath, based on DME.Taken that is hard to find an ILS CAT I approach that can't be downgraded to LLZ which means the DME checkpoints are mainly there for that reason, but I'd still crosscheck the DME at those points or assign that task to the PNF if flying 2crew. If you don't have a backup, how do you know the GP is operative? It would be foolish not to use a crosscheck method when it's available.

[woodhick 504]

Aside from all the you gottas, do not, do to stuff I've already plowed through, you do not need DME for your ILS approach for another simple reason. While this applies more easily in the U.S. than other countries when it comes to flights simming, where is your approach plate when making your approach? Don't have one, don't use one? Why not!! The various distances, and a whale of a lot more are all there for your edification and elucidation. In the U.S. there are any number of places to get free approach plates and other info besides. Here's one.I always feel somewhat naked and uninformed when flying without an approach plate for my landings.

[threelittlefish 0]

Point taken, and I'd love to agree with you, but you're wrong.One little thing first, ILS approaches don't have FAFs, they have FAPs. Only non-precision approaches have FAFs.And then, check this plate as an examplehttps://ais.fi/ais/eaip/aipcharts/efhk/hk22Lilscat2.pdfit's CAT II ILS only approach (not a LOC app, GS is required). Note DME required and and the height check points along the glidepath, based on DME.Taken that is hard to find an ILS CAT I approach that can't be downgraded to LLZ which means the DME checkpoints are mainly there for that reason, but I'd still crosscheck the DME at those points or assign that task to the PNF if flying 2crew. If you don't have a backup, how do you know the GP is operative? It would be foolish not to use a crosscheck method when it's available.

A CAT II approach is an autopilot approach. The DME info there is provided in lieu of marker beacons I would imagine. I can't see any other reason for it. ILS fascilities are self testing any fault out of parameter and the you will get an appropriate flag. I knew you would find some oddball example of such an aproach. I've beenflying for 24 years 15 with airlines and never used DME on an ILS CAT III approach.

[mgh 89]

Even if there is a DME it generally is not at the threshold.scott s..

It doesn't have to be. Many airport DMEs are zero-ranged to the threshold regardless of their physical location.