Cleared for the approach in the US,

[skol]

Have a question for US Controllers.
Arrived over Seal Beach from the South Pacific at 7000 ft. After Seal Beach VOR received from LAX ATC "cleared for the approach 25L", no altitude mentioned. Commenced descent to intercept LOC and GS and at 4500ft LAX ATC said "you appear to be descending". Levelled off at 4500 and intercepted ILS. No more said; would be grateful if someone could clarify this one.
Thanks

[76mike]

Doesn't the transition from Seal Beach say 5000'?

[heloguy412]

When I did the Instrument Check Pilot course, the one thing we were told as Canadian flyers that would screw you up in the States was descending when cleared for the approach.. Unless you are on a segment of said approach you have to maintain altitude unless cleared to descend.

Cheers

[slatch]

76mike has it correct. from Seal Beach for 25L you maintain 5000 until intercepting the glideslope. For 25R you decend to 5000 unless they give you 3700 (rare, this is also applicable to the 25L CAT III approach). For the 24's you decend to 4000. Seeing you were assigned 25L as soon as the controller saw you leave 5000 he questioned what you were doing. Seeing the MEA is 3700 he/she did not need to climb you back up to 5000 unless there had been traffic. The decent altitudes are on the approach charts.

[aterpster]

Slatch:

76mike has it correct. from Seal Beach for 25L you maintain 5000 until intercepting the glideslope.

That is more than what 76mike stated. Below is the Jepp approach chart. Indeed, 5,000 is the segment altitude from SLI to GAATE. Not only did the clearance require the pilot to not descend below 5,000 per the SLI-GAATE segment, the clearance required him to treat GAATE as a step-down fix, not the G/S intercept point. Further, inbound on the localizer he was required to treat HUNDA as a step-down fix (3700) then intercept the G/S at the precision final approach fix; i.e., intercept the G/S at 1,900, approximately at LIMMA depending on atmospheric conditions. The Ball Note 2 in the profile view does permit ATC (not the pilot) to assign a G/S intercept of 5,000 or 3.700. Based on what the OP stated, ATC did not exercise that charted option.

http://i201.photobucket.com/albums/aa214/aterpster/JeppLAXILS25L.jpg

[nktatc]

Unless things have changed an altitude to maintain until established on a segment of the approach is required. In the initial post they say they were cleared for the approach and started to descend as they joined the GS. I take it from the info provided it's an ATC Snafu.

[KKoran]

The initial post says they were cleared for the approach after they had crossed the Seal Beach VORTAC. Assuming they were on the 355 radial (or still "over" the navaid),the controller did not have to issue an altitude to maintain because they were on a published segment of the approach.

The original poster obviously didn't provide a transcript-quality review of what was said. As an ATC manager, I investigated numerous incidents. There are usually three sides--what the pilot says happened (usually not quite correct), what the controller says happened (likewise, ususaly not quite correct), and what the tapes say (usually some where between what the pilot and controller think happened, but occasionally one has to wonder if it was the same incident).

[nktatc]

If they are inside Seal Beach an Alt. for the next segment would be required. ATC comments that they are descending and then no more.... An alt assignment would have clarified all this. If we follow the KISS principle it's less likely Mr. Murphy will step in.

[KKoran]

An altitude was required and an altitude (5000) was provided--on the approach plate.

[411A]

This incident reminds me of the TWA flight that crashed many years ago, approaching IAD...IE: not paying attention to what is on the approach chart, and descending pell mell toward the final approach fix altitude.
It was wrong then...and wrong today.:eek:

[KKoran]

411A,

Not quite. In the case of the TWA 514 accident (http://libraryonline.erau.edu/online-full-text/ntsb/aircraft-accident-reports/AAR75-16.pdf) there was no altitude on the approach chart for them to comply with because they hadn't yet reached the published procedure. The controller cleared them for the approach and the crew descended before they got to a published segment of the approach, hitting the top of a mountain in the process.