STARS and Altitude/Speed Restrictions

Questions and comments about the PE Pilot Training Program

STARS and Altitude/Speed Restrictions

Postby Mark Hargrove » Sun Jan 29, 2012 5:26 pm

I'm practicing for I5 and have few of questions:

First, I'm going to be flying a Citation Mustang for the route. The instruction for the rating says to fly the KLAS CLARR2 arrival for jets and to fly CRESO3 for turboprops. The Citation Mustang is a jet, but it cannot meet the crossing speed restriction of "at 250K" at CLARR -- the Mustang redlines at 250 Kts IAS, and normal cruise is about 235 Kts IAS. Does this mean I cannot fly the CLARR2 STAR?

Second, the CRESO3 calls for an altitude crossing restriction of "at FL240" for JOKUR intersection. Does this imply that I cannot file a flight plan for lower than FL250 enroute from KBUR (since the direction of flight requires an odd altitude). Said another way, does this restriction mean that a pilot cannot fly the CRESO3 arrival with an enroute altitude of, say, FL230 ft? (or does it mean that I could file a flight plan with an enroute altitude of FL230, but would then have to climb 1,000 feet in time to meet the JOKUR restriction?

Finally, flying the published ILS 25L approach at KLAS takes you from BLD VOR at 8000' out to PRINO intersection as the IAF (requiring a more than 300 degree left turn at PRINO to the final approach course!) then requires a relatively rapid descent down to 6500' for LARRE and 4900' for SHAND before intercepting the GS at the final approach fix at 3800' at RELIN. As if this wasn't crazy enough, the Flight1 Citation Mustang absolutely cannot capture the glideslope for an autopilot-coupled approach from above the GS -- it has to capture from below. The depicted descent profile on the approach chart never seems to give me the opportunity to be below the GS for a capture -- I've flown the approach a half-dozen times now (from BLD) and just don't see how to avoid needing to hand-fly the approach all the way to the FAF (at least), then hoping to get GS capture inbound from RELIN. For the PE I5 checkride, am I going to have to deal with this, or is it more common to be vectored to the final approach course after crossing BLD at a reasonable altitude that allows a below-glideslope capture?

Thanks!

-M.
Mark Hargrove
Longmont, CO
PE: N757SL (Cessna 182T 'Skylane'), N757SM (Cessna 337 'Skymaster'), N757BD (Beech Duke Turbine)
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Re: STARS and Altitude/Speed Restrictions

Postby Mark Hargrove » Sun Jan 29, 2012 6:11 pm

In fact, after some extra study of the arrival and approach plates, I see that the "leg" from BLD to PRINO isn't even flyable -- it's just a radial indication. How the heck do you get from BLD to the approach? Sure, I understand that under normal conditions you'd be vectored, but what happens if you've lost comms?
Mark Hargrove
Longmont, CO
PE: N757SL (Cessna 182T 'Skylane'), N757SM (Cessna 337 'Skymaster'), N757BD (Beech Duke Turbine)
Mark Hargrove
 
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Re: STARS and Altitude/Speed Restrictions

Postby Keith Smith » Sun Jan 29, 2012 10:18 pm

As you've correctly determined, the ILS 25L isn't flyable from BLD. In a lost comms situation, I'd just shoot the visual since LAS is VFR 99.9% of the time. The KEPEC RNAV arrival is another choice as it takes you to PRINO, from which you could fly on of the instrument approaches if needed.

The CRESO arrival does not call for FL240 at JOKUR. The Minimum Enroute Altitude (MEA) for that segment is 10,000ft. The FL240 is what to expect for a turbojet, but it's not a requirement of the STAR.

I'm not sure about the speed restriction, that's a great question. Practically speaking, the difference between 235kias and 250kias is not sufficient enough, in my mind at least, to pull someone off the arrival. It is to ATC's advantage to have you on the STAR as much as possible under heavy traffic conditions to minimize the vectoring until as late as possible. Could you legally file it, knowing you couldn't comply with a published restriction? I'm guessing the answer is no, but would definitely like someone else to weigh in on that one if possible. For I-5 test purposes, go ahead and file it, and then just advise ATC you're unable 250kts when you're talking to the center controller. The goal of that rating is to see if you can fly the STAR. The fact that you have noticed the 250kias restriction and are thinking about it is great. The fact that you can't quite hit 250kias is not a problem for us here, per se.

Regarding the gradient on the ILS approach, I don't see an issue there. The descent gradient required to comply with the minimum altitudes at each fix along the approach seem reasonable. What are you seeing that seems out of the ordinary regarding the vertical profile?
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Re: STARS and Altitude/Speed Restrictions

Postby Mark Hargrove » Mon Jan 30, 2012 8:31 pm

After looking again at the STAR plate from AirNav.com I do indeed see that the annotation at JOKUR is simply 'expect to cross at FL240'. Curiously, the EFB software I run (from AivlaSoft) renders the intersection with a horizontal bar above and below the altitude at JOKUR on the CRESO3 STAR which is what misled me. It makes a LOT more sense that it's simply an 'expect' for jets arriving from higher FL's.

Thanks for the advice on the speed restriction flying the CLARR2 as part of I5. It does seem kind of odd to have such a precise speed crossing restriction. "At or below 250K" seems like it would be more practical, especially for bizjets that don't have autothrottles.

It's probably not so much the gradient on the ILS as much as my inexperience with instrument approaches. I try to be very careful to arrive at instrument approach intersection markers at or slightly above the specified altitude, and never below them (unless I've been cleared to do so by ATC). When I follow the descent profile from PRINO using that philosophy, I'm never actually below the glideslope and the Citation Mustang's autopilot won't capture the GS from above (even from just a just a single dot above). If you've never been below GS for the capture, you're flying the darn thing by hand until you've got the needle pretty much exactly on the money -- and even then, I cannot reliably get the G1000's AP to capture. It's very odd, because other aircraft I fly from Flight1's stable of G1000-based cockpits (like the C-182T) have no problem with the capture. It's the only downside to the Citation Mustang for me at all -- it's otherwise a wonderful plane to fly.

-M.
Mark Hargrove
Longmont, CO
PE: N757SL (Cessna 182T 'Skylane'), N757SM (Cessna 337 'Skymaster'), N757BD (Beech Duke Turbine)
Mark Hargrove
 
Posts: 401
Joined: Thu Dec 22, 2011 11:42 pm
Location: Longmont, CO


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