Hmm interesting. So only sometimes you need DME even though you mostly wont use it. Sounds like the FAA to me!
Wait the FAA does mandate this right? you need all 5? I could check the FAR but im lazy.
No, a DME is not required for all ILS approaches; however, there are some ILS/DME approaches that require it. Normally it's because they have an arc or the distance is needed to locate a fix on the approach.
Not an instrument pilot, right? It sounds like you may have misunderstood something you heard along the way. Perhaps you can provide a reference to the "5 components" you say are required? I know 5 components to an ILS system. None are DME and only three are required.
The Note section on that "Z" approach looks disgusting. There ought to be a way to clean that up.
Yep. "Not much" is an understatement. There isn't any information on the plate to help you identify the IAF other than DME. That's why it's Required:
First off, there are three functional components: guidance, range and visual. This has long been fodder for FAA written test questions. DME can substitute for marker beacons within the range component. The "pointless" comment regarding DME probably has to do with dropping it from the title of ILS approaches that offered DME a few years ago. It was deemed unnecessary to navigate an ILS final approach course so, IIRC, they purged the /DME from the title (a slash means "and"). In the case of LOC only approaches, though, DME may still be required to navigate final. I'm curious what the five components were.
Much better. Being lazy, though, I'd have simply printed the Raleigh minimums and noted to use the Raleigh altimeter if the local one was unavailable. I doubt more than one or two flights per year would miss the approach because of the difference while more than that might crash trying to fly and read the current notes at the same time.
ILS/DME is an obsolete naming convention. If DME is required it will now be in the plan view for procedures revised subsequent to the naming convention change.
Good reason I can't find one, eh?
There's no such thing as a "GPS waypoint". There are only waypoints or fixes. How you navigate to them will vary and does not require GPS. They are other ways to achieve the same required navigation performance. Navigation systems that incorporate GPS/GNSS updating will have the lowest RNP/ANP values and will be required for certain procedures but that's not required to fly most RNAV routings or to navigate to any waypoint or fix.
Indeed they are but not RNAV-1 nor RNP APCH.
If DME is in the planview, it is required. The naming convention was changed to conform with ICAO, but because DME is no longer required in some ILS IAPs.
How many angels on the head of a pin? As an example, if you don't have DME or GPS-RNAV, you cannot fly the KLAX ILS 25L without DME unless you can get ATC to call out all of those DME or RADAR fixes.
According to some FAA AC you can identify such fixed if you have a "suitable" RNAV equipment in lieu of DME.
That was not part of it when I did the IR. I could be wrong.... mine was 1985-1986 ish.
I'll quote my previous message in pertinent part, "if you don't have DME or GPS-RNAV, you cannot fly the KLAX ILS 25L without DME unless you can get ATC to call out all of those DME or RADAR fixes."
Adding to that bit of trivia, some DME ground stations can handle a maximum number of interrogations from aircraft at one time. If I recall correctly, some are 100, some are 200.
About 15 years ago, FAA issued a letter that said an approach certified GPS was approved to ID marker beacons, NDB's, DME fixes, etc. It showed up in my Jepp updates. Maybe its an AC now?
About 10 yrs ago pilots operating in and around the Gulf of Mexico were submitting reports to the FAA that the White Lake Vortac (LLA) was weak and puny in its output, especially DME. You could only get DME inside four miles. A gent from the FSDO showed up to speak to a group of pilots and touched on the low power of the facility. He said "Lets check AIM for a revue. Your equipment sends an interrogation to the facility and it pings back to you. If there are lots of hits, the facility goes into defensive mode and shifts to low power." So all present counted up the number of DME units in the air at that time & place. Midweek, between New Orleans and Beaumont. Couple hundred Helos, lots of GA airplanes passing by, all the air carrier traffic to and from S & Central America. Could be several hundred in range of LLA. Even though everybody is using GPS, you ought to do something with your VHF Nav. It is prudent to tune it to the closest facility just in case. Case solved. BTW, I always got a good "hit" after midnight.
Reminds me of a story. On the day after the 9/11 attacks, a fellow CAP pilot and I were tasked with flying blood samples from Oakland to the Red Cross lab in Portland, OR. This was needed because donated blood has to be tested before it can be used, they only had two labs on the West Coast, and nearly all civilian air traffic was grounded that week. On the way home, since there were so few aircraft in the air to compete for the attention of the DME ground stations, we were checking to see how many of them we could pick up. We were surprised to see the unit display a distance greater than a hundred miles. My colleague commented that he didn't even know that a DME could display that many digits to the left of the decimal point!
In the flight levels I've seen them lock on close to 200 miles. (H VOR)
Although there may be times that DME is nice to have for situational awareness, most times it's not required. I wouldn't go so far as to say it's pointless though.
