Gulfstream V / G500 / G550
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 120; Flight Crew Total 14500; Flight Crew Type 600
Human-Machine Interface; Time Pressure; Confusion; Distraction; Situational Awareness
Deviation - Altitude Crossing Restriction Not Met; Deviation - Speed All Types; Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Clearance
Flight Crew Returned To Clearance
Aircraft; Procedure; Human Factors; Chart Or Publication
Descending on the EAGUL5 into PHX; Center cleared us direct HOMRR with no speed restriction until reaching HOMRR. The STAR requires crossing HOMRR at or below 16;000 FT at 250 KTS. The FMS was programmed with the arrival; and VNAV was selected as well. All seemed well as we descended to and crossed HOMRR at 16;000 FT/250 KTS. However the next fix VNNOM required crossing between 11;000 FT and 10;000 FT VNNOM is 4.1 NM from HOMRR. Crossing HOMRR at 16;000 FT; we realized that it was almost impossible to lose 5;000 FT to 6;000 FT in 4.1 NM. At this point I clicked off the automation and pointed the nose down; achieving a descent rate of better than 6;000 FPM. Our airspeed increased to 280 KTS and we crossed VNNOM high and fast. I do not believe that we caused a conflict with any other aircraft.I have flown many; many VNAV STARs in this aircraft; and it has never been off before. The STAR called for crossing HOMRR at or below 16;000 FT; and the FMS should have been in a position to make the next subsequent fix.Obviously we could have done a better job monitoring the situation; however this occurred during an extremely high workload period. We made; programmed and verified 2 runway/ approach changes during this descent prior to HOMRR. In fact the first change went from a landing east flow to a landing west flow. This could actually explain why the FMS logic chose 16;000 FT at HOMRR instead of lower....Landing east on the EAGUL5 requires crossing a different fix immediately past HOMRR (SMAAK) between 15;000 FT and 14;000 FT.This is a really poorly designed STAR. Something should be done to warn other crews not to fall into the same trap that we did.
When; while descending via the EAGUL RNAV STAR to PHX; their FMS system failed to compute the need to cross HOMRR well below the maximum 16;000 FT in order to cross VNNOM 4.1 NM later between 11;000 FT and 10;000 FT; the flight crew initiated an expedited descent and exceeded the 250 KTS charted max IAS. Multiple runway changes by ATC; including a switch from a downwind arrival to land east to straight in to land west were cited by the reporter as likely contributing factors.