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Controller goof, part of the test, or just a lesson learned?

Posted: Wed Feb 07, 2018 6:14 pm
by MALL
Last Thursday evening, 1 Feb, I did the Cat-6 rating, and had what I thought a noteworthy experience on which I would like some feedback from the powers that be. After being handed off to Joshua Approach, I was soon told to "report airport in sight and descend at my discretion". I was abstaining from GPS, and thought, "wow, pretty good groundspeed for 105kts TAS." Anyway, I could just make out an airport in the bend of Highway 58 in the distance, but waited a bit to report the airport in sight in order to be sure. Soon, I did, however, see it more distinctly, call approach and throttle back to begin a slow descent to pattern altitude (3,801) from 7,500. Immediately I was told to contact tower and report downwind, right-traffic for runway 26. As I neared "the" airport, I noted it had a runway of the correct orientation, but the ground was looking awful close at 4,500. I entered the pattern and reported downwind, (receiving no answer from tower) but couldn't make out any other runways that were supposed to be there, and finally realized I was at KTSP and only halfway to KMHV. I then climbed back to about 1,500 AGL and completed the flight to KMHV.
So, what I learned should be obvious, one is always responsible for his own navigation, BUT, it does seem I was perhaps led astray, given I had flight following, and was cleared to descend well before I was in a logical place to make my descent into Mojave, and turned over to the Mojave tower when I was still well west of Tehachapi. Keith et al, I'm interested to hear what you might have to say. Thanks.
Michael

Re: Controller goof, part of the test, or just a lesson lear

Posted: Wed Feb 07, 2018 7:16 pm
by Kevin_atc
I’m likely somewhat bias in favor of the controller, but I don’t see any fault on the controller’s side. Especially considering you were VFR, the controller told you to descend at your description (something that didn’t even need to be said) and report the field in sight. You did both of those things and gave the controller no reason to think otherwise. According to Sky vector, the airports are only 15 miles apart therefore I don’t think it’s unreasonable for ATC to think you have the airport in sight and let you go on your own.

I also think it should be clarified that the controller didn’t “clear” you to descend. Had you been IFR and the controller had given you a descent clearance 50-100 miles further out than you had expected, that may be a different situation. But in this case, since you were VFR, you are permitted to begin your descent at any time.

Re: Controller goof, part of the test, or just a lesson lear

Posted: Thu Feb 08, 2018 9:53 am
by MALL
Kevin, thanks for your reply. I'm not clear on what you mean by "You did both of those things and gave the controller no reason to think otherwise." What should I have done to make him think otherwise? If Approach is providing flight following, part of which I thought was helping a VFR pilot avoid terrain in the dark, the controller thinking I have the airport in sight, and suggesting I descend when I'm 30 miles west of my destination when I only have about 2,000 ft of terrain clearance seems inconsistent with the objective of flight following. I don't know-- I'm asking. I acknowledged that I made a mistake, and in no way want to be defensive about this, rather learn as much as possible. I don't know what a controller sees, and had thought perhaps he too mistook my whereabouts.

Re: Controller goof, part of the test, or just a lesson lear

Posted: Thu Feb 08, 2018 10:44 am
by Kevin_atc
I didn’t hear the exchange with ATC, but according to your post, the controller told you to “Descend at pilot discretion” which in no way meant you needed to descend right at that moment. The controller is simply telling you (again, unnecessary since you’re already VFR) that whenever you want to begin your descent, that’s fine by him. The controller doesn’t care when you begin your descent if you’re the only airplane out in a non-populated area- that goes for IFR too. So, had it been me flying, I probably would have stayed level for another 10-15 minutes before starting down.

Lastly, I know you thought you had the correct airport in sight, but if you are ever in doubt that you are being told to descend too early- ASK! Even in the real world, the controller may think you are landing somewhere else than you are planning. Especially if you are VFR, occasionally ATC will input the incorrect destination into their system.

Re: Controller goof, part of the test, or just a lesson lear

Posted: Thu Feb 08, 2018 11:27 am
by Keith Smith
ATC's primary responsibility is to separate aircraft where separation is required. That would be IFR from IFR, and IFR from VFR in Class B/C airspace, and VFR from VFR in Class B airspace.

On a workload-permitting basis, ATC can provide radar services to VFR aircraft (commonly known as Flight Following). This includes traffic advisories (not relevant here) and safety alerts. Safety Alerts include warnings if the aircraft is believed to be getting close to terrain. However, the AIM (5-5-7) says this about Safety Alerts:
2. Be aware that this service is not always available and that many factors affect the ability of the controller to be aware of a situation in which unsafe proximity to terrain, obstructions, or another aircraft may be developing.

b. Controller.

1. Issues a safety alert if aware an aircraft under their control is at an altitude which, in the controller's judgment, places the aircraft in unsafe proximity to terrain, obstructions or another aircraft. Types of safety alerts are:

(a) Terrain or Obstruction Alert. Immediately issued to an aircraft under their control if aware the aircraft is at an altitude believed to place the aircraft in unsafe proximity to terrain or obstructions.
The only terrain data we have is a MVA map which provides at least 1000ft of obstacle clearance in normal areas, and 2000ft of obstacle clearance in mountainous terrain. VFR aircraft routinely fly below the MVAs as a matter or normal VFR operation. As a result, our ability to issue safety alerts is minimal.

Kevin is correct that a pilot's discretion descent is in no way an implication that you SHOULD start descending. He's also correct that it's technically unnecessary for a controller to even issue that to a VFR aircraft unless a previous altitude restriction was given (which is rare outside of Class B/C airspace).

If you would like a direct response from the 'power that be' regarding a specific flight, I would suggest using the address listed on the Contact page on the web site, ops@pilotedge.net. The forum is largely for peer-to-peer support and discussion. It's hard for us to keep up with every thread in every forum, so if you're specifically seeking an answer from us, email is the best way. If you'd like the share your experience and insight gained from it on the forum, that is great and is actively encouraged, too.

Re: Controller goof, part of the test, or just a lesson lear

Posted: Thu Feb 08, 2018 11:38 am
by MALL
Keith, thanks for your, as always, thorough explanation. Your knowledge of the system is impressive by any measure, and I'm grateful to profit by it. Apologies for posting in the 'wrong' place: I'm still learning to navigate the fora; I'm glad you and Kevin found my query here.

Re: Controller goof, part of the test, or just a lesson lear

Posted: Thu Feb 08, 2018 11:48 am
by MALL
Kevin, thank you as well for your follow-up.