what minimum navigation equipment is required to complete the vor/dme-a procedure?
Subscribe today to Airplane & Pilot mag for industry news, reviews and much more than delivered straight to yous!
It all started with on weird note on the ILS Z or LOC Z Rwy 23 at Walterboro, South.C. (KRBW). The note says: "GPS and DME required (emphasis mine).
Back when I learned to wing, a GA airplane with altitude measuring equipment, or DME, was loftier-tech ride to brag over: "It actually shows yous how far you are from a VOR station! And your groundspeed! Well, presuming y'all're flying directly towards or away from the station …"
At present GPS lets my phone spit times and distances to iv different Starbucks dispensaries within the surrounding viii blocks, complete with verbal directions. Likewise, GPS in the cockpit makes DME an eBay novelty. Y'all can substitute GPS for a DME requirement in virtually every state of affairs—so how tin can an arroyo require both?
It doesn't. You can wing this approach with only an approved GPS. Now come up downwardly the rabbit hole with me to sympathise why that'due south truthful. Spoiler alert: This discussion might reveal that you've been reading approach charts wrong for years.
Letters in Approach Titles: And so and Now
First a bit of background: Dorsum when DME was the flop, the merely unmarried letters yous saw in a approach titles were from the commencement of the alphabet, such as the VOR/DME-A approach to Augusta, ME (KAUG). (These were also the days when a cell phone's only function was making phone calls. The dark ages, for sure.)
Replacing a specific runway with a letter in the approach title means that only circumvoluted minimums are available. This happens when the last approach course doesn't align within 30 degrees of a track, the descent from MDA to the runway would be too steep for a straight-in, or the runway environment lacks required items for straight-in minimums. Required items include things like runway markings and lights. If any of those criteria are truthful (the VOR/DME-A at KAUG meets the third i), no straight-in minimums are published even if the final approach course aligns with a rails. Only circling minimums are published and the approach is to all approved runways. Yous can notwithstanding land straight-in if you want, but that'southward for another discussion.
Letters from the tail finish of the alphabet (X, Y, and Z) identify multiple approaches to the same specific runway, so you'll always see a rails named in the approach title. Most oftentimes, the Z allows lower minimums by requiring a higher climb slope for the missed approach. The Y and Z versions of the ILS or LOC/DME Rwy xix at Rutland, VT (KRUT) are affiche children for this. The Z version has a DA 600 feet lower, merely requires 370 anxiety per NM on the missed arroyo if it doesn't work out. (The charts for these approaches take so many notes the plan view area is compressed but to make room. Check 'em out some time.)
The other common reason for multiple versions is unlike equipment requirements, and that'southward what's happening at KRBW.
Beginning with the Y approach. This is a conventional ILS, with a requirement for DME stated in the notes. The question is: What for? Information technology can't exist for a transition from the enroute environment because those notes appear on the programme view, not in the notes section. The IAF at LAMKE is a prepare on V18-311, and then you lot can become there by VOR. VOR capability (or GPS equivalent) is assumed, so it'southward never stated as a requirement. An ILS never requires DME for identifying the FAF or DA considering the FAF is glideslope intercept and DA is by altitude. Cross-check of glideslope intercept altitude is a good thought, only it's never required. The missed approach goes to STOAS, but that can be identified as an intersection of 2 VOR radials.
The answer is that DME is just required for the localizer approach. At that place's no other fashion to place the FAF at DOTMY or the missed arroyo signal at 1.i DME on the localizer. Annotation that there'south no timing published for FAF to MAP.
If you're flight the ILS y'all do not need DME on the aircraft. Yes, that's correct, if y'all wing the ILS you may ignore that note.
Earlier you printing send on the e-mail telling me notes aren't optional, empathize that this nautical chart displays two separate approaches, co-charted. The ILS approach is a unlike arroyo with different obstacle requirements and different procedures than the localizer approach. The reason they share a chart is historical. Exercise you recall paper charts that we used to tote around in hernia-inducing binders? (If not, Google it on your "phone.") Most every ILS had an accompanying localizer approach that shared well-nigh of the same information. Co-charting the two approaches kept those binders a few kilos lighter.
This truth applies to your approach request. You ask for the ILS or the localizer and get cleared equally such, "… cleared ILS Runway Two Three arroyo …" not "… cleared ILS or localizer Track Two Three approach." If you switch from one to the other part mode, say considering the glideslope failed, technically you should get a new clearance. No one cares in practice, but that's another discussion likewise.
This fact that it's two approaches is why the correct name is: "ILS Y or LOC Y Rwy 23" rather than what "ILS or LOC Y Rwy 23."—and, yes, that ways the title of the Y and Z approaches at KRUT are wrong (equally are many others). This reveals how deep the confusion goes. The charting office even had to straighten themselves out. Expect the incorrect titles to change as charts are updated.
Now that we accept this nomenclature straightened out, check out the Z approach at KRBW. GPS is used for transition from the enroute environment with no-PT sectors assuasive direct LAMKE. That'southward a corking do good for GPS-equipped shipping, but it's not required because you could get in at LAMKE via airway, simply similar the Y approach. The DME requirement in the notes section is for the aforementioned reason as the Y chart: it'south only for the localizer version. Per FAA policy, you may substitute GPS.
Yet, the Z approach has a different missed arroyo process in that you go GPS-direct to STOAS rather than intercepting a radial east of STOAS and then proceeding outbound. This requires GPS—and applies to both the ILS and the localizer approaches.
Therefore, what "GPS and DME required" should actually say is "GPS required for ILS Z or LOC Z missed arroyo procedure. DME required for LOC arroyo, and you can substitute GPS for that if y'all want."
And that's essentially what the FAA will be doing in the future. A new area in the briefing strips will specify what's required for what. I don't accept the details, but I'll be happy to run into it put into consequence.
At present I hear the weep: "If GPS is required no matter what, and GPS can substitute for DME, why bother saying DME is required at all?" In this example, there's no proficient reason other than consistency. However, if the Y and Z had unlike minimums y'all could, in theory, enquire for a missed approach procedure that didn't crave DME and thereby obviate the need.
At least, that'south the way I think about it. I've never seen guidance or an FAA position on this, but I tin can tell you in practice nosotros used to practise this all the time where approaches required equipment for a missed nosotros didn't have installed. We requested alternating missed approach instructions from ATC and got on with business. No one complained or gave united states of america a number to telephone call on landing.
I'm non saying that's an approved procedure, only it does point out how understanding all those notes on the chart is essential to your strategy for flying an musical instrument approach.
Preparing for Your Y or Z
There'south an interesting practicality of this having two approaches co-charted when it comes to loading the approaches from a GPS database. Notation on the ILS Z or LOC Z Rwy 23 at KRBW that there'due south a stepdown within the FAF at ZILTA. Identifying ZILTA lets you descend from 680 MSL to the minimum of 480 MSL.
It used to be y'all'd only run across the ILS approach in the GPS database. That arroyo might—or might not—contain a stepdown ready like ZILTA. If it didn't, you'd have to do the math that ZILTA was 1.7 miles from the threshold of Runway 23.
It turns out that if you purchase your information from Jeppesen, you still do this math. If you buy your North American information from Garmin, still, there are two approaches in the GPS database, one for the ILS without ZILTA in the flight plan, and one for the localizer arroyo with ZILTA in the flight plan. It's not a large bargain, but it's worth knowing if you're loading approaches or choosing your database vendor.
Or you could only invest in that vintage DME on eBay to brag that you can fly an airplane—or notice a Starbucks—without no stinkin' GPS.
You tin read more on this discipline, or other instrument flying topics, in Jeff'southward IFR Focus blog.
Want more articles on instrument flying and related VFR options? Check out our Inside IFR archive.
Source: https://www.planeandpilotmag.com/article/why-would-you-need-both-gps-and-dme/
0 Response to "what minimum navigation equipment is required to complete the vor/dme-a procedure?"
Enviar um comentário