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A lear 45 flight crew; lacking sophisticated autoflight VNAV and autothrottle availability; failed to make the crossing restrictions at vnnom on the eagul RNAV STAR to phx. The reporter cited the excessive complications of this and other complex RNAV stars; which require excessive flight crew workload to reconfigure and program their FMS to meet those demands.
| Attributes | |
| ACN | 1171738 |
| Time | |
| Date | 201405 |
| Local Time Of Day | 1801-2400 |
| Place | |
| Locale Reference | P50.TRACON |
| State Reference | AZ |
| Environment | |
| Flight Conditions | VMC |
| Light | Dusk |
| Aircraft 1 | |
| Make Model Name | Learjet 45 |
| Operating Under FAR Part | Part 135 |
| Flight Phase | Descent |
| Route In Use | STAR EAGUL5 |
| Flight Plan | IFR |
| Person 1 | |
| Function | Captain Pilot Flying |
| Qualification | Flight Crew Multiengine Flight Crew Instrument Flight Crew Air Transport Pilot (ATP) Flight Crew Flight Instructor |
| Experience | Flight Crew Last 90 Days 100 Flight Crew Total 10000 Flight Crew Type 150 |
| Events | |
| Anomaly | Deviation - Altitude Crossing Restriction Not Met Deviation - Procedural Clearance Deviation - Procedural Published Material / Policy |
Narrative:
I question the design of this arrival; specifically the descent profile [between] homrr intersection and vnnom intersection.today after crossing homrr at 16;000 feet and 250K; I discovered that I was unable to cross vnnom at 11;000 feet. Why was that? The reason was that the two intersections are only 4.1 nm apart. That takes a minute at 250K and would require a 5;000 FPM descent rate. While my aircraft is capable of descending at that rate; to do so that quickly would have required some extreme pitch changes; negative G forces; and created a hazard for my passengers.after further review of the procedure I noticed that the procedure gave us the option of crossing homrr at a lower altitude. With the experience of flying it once behind me; I would be able to anticipate this and would do just that.that brings me to my original point that this procedure needs to be better designed as I believe it is overly complex. From the time I leave cruise altitude until joining the approach; I have 9 crossing restrictions and 3 airspeed adjustments to plan for. Seven of the crossing altitudes introduce an additional complication of giving me a block of altitudes at which to make the crossing. My FMS is a wonderfully capable device; but it does not know how to cross a fix at more than one altitude. This requires me to manually program all these crossing restrictions and determine what altitude I wish to enter.suffice to say that makes this a very busy arrival for both pilots and a tricky nuance like the homrr to vnnom transition is hard to foresee and plan for.two suggestions here. At the very least; please fix this specific problematic procedure. Better yet; simplify these procedures. If it is necessary to fly this with so many requirements; make the requirements more straightforward. Do away with the block altitudes and at or below and make sure that aircraft can actually meet all that ATC is asking.
Original NASA ASRS Text
Title: A Lear 45 flight crew; lacking sophisticated autoflight VNAV and autothrottle availability; failed to make the crossing restrictions at VNNOM on the EAGUL RNAV STAR to PHX. The reporter cited the excessive complications of this and other complex RNAV STARs; which require excessive flight crew workload to reconfigure and program their FMS to meet those demands.
Narrative: I question the design of this arrival; specifically the descent profile [between] HOMRR intersection and VNNOM intersection.Today after crossing HOMRR at 16;000 feet and 250K; I discovered that I was unable to cross VNNOM at 11;000 feet. Why was that? The reason was that the two intersections are only 4.1 nm apart. That takes a minute at 250K and would require a 5;000 FPM descent rate. While my aircraft is capable of descending at that rate; to do so that quickly would have required some extreme pitch changes; negative G forces; and created a hazard for my passengers.After further review of the procedure I noticed that the procedure gave us the option of crossing HOMRR at a lower altitude. With the experience of flying it once behind me; I would be able to anticipate this and would do just that.That brings me to my original point that this procedure needs to be better designed as I believe it is overly complex. From the time I leave cruise altitude until joining the approach; I have 9 crossing restrictions and 3 airspeed adjustments to plan for. Seven of the crossing altitudes introduce an additional complication of giving me a block of altitudes at which to make the crossing. My FMS is a wonderfully capable device; but it does not know how to cross a fix at more than one altitude. This requires me to manually program all these crossing restrictions and determine what altitude I wish to enter.Suffice to say that makes this a very busy arrival for both pilots and a tricky nuance like the HOMRR to VNNOM transition is hard to foresee and plan for.Two suggestions here. At the very least; please fix this specific problematic procedure. Better yet; simplify these procedures. If it is necessary to fly this with so many requirements; make the requirements more straightforward. Do away with the block altitudes and at or below and make sure that aircraft can actually meet all that ATC is asking.
Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.