37000 Feet | Browse and search NASA's Aviation Safety Reporting System |
|
Attributes | |
ACN | 1207796 |
Time | |
Date | 201410 |
Local Time Of Day | 1201-1800 |
Place | |
Locale Reference | DFW.Airport |
State Reference | TX |
Aircraft 1 | |
Make Model Name | A321 |
Operating Under FAR Part | Part 121 |
Flight Phase | Descent |
Route In Use | STAR SEEVR1 |
Flight Plan | IFR |
Component | |
Aircraft Component | FMS/FMC |
Person 1 | |
Function | Pilot Flying Captain |
Qualification | Flight Crew Air Transport Pilot (ATP) |
Events | |
Anomaly | Aircraft Equipment Problem Less Severe Deviation - Altitude Undershoot Deviation - Altitude Crossing Restriction Not Met Deviation - Procedural Clearance Deviation - Procedural Published Material / Policy Deviation - Speed All Types |
Narrative:
Descending into dfw via the SEEVR1 arrival; we were given descent to F240 outside of prowd. We had not yet descended all the way to F240 when we received a frequency change and the next controller cleared us to descend via the SEEVR1; runway 12L. The captain and first officer agreed that 7000 feet was the correct setting and the altitude was set. As we continued with the programmed descent we noticed that FL280 was displayed as a temporary constraint in the bottom corner of the primary flight dispaly (pfd). Neckk (our upcoming fix) has constraints of F280-F240 and 290 kt. Since the F280 in the pfd did not violate the neckk window and every indicator showed us on profile; we saw no reason to intervene. The aircraft crossed neckk at F280 and 290 kt. The next fix is naavy with constraints of F230-F210 and 290 kt. The aircraft pitched down in an effort to pass through the naavy window; but there is only 10 miles between the two fixes and started indicating that it would be high at naavy. We extended partial speedbrake and that was insufficient. We then extended full speedbrake and it was still insufficient. I selected open descent and selected a higher speed in an effort to return to the altitude profile. We reached F230 within about 2 miles past naavy and restored the automation to the managed mode for the remainder of the profile. This arrival was recently created. We believe that there is either a design flaw in the SEEVR1 or a database error in the FMC.the argument for the database error is that there is not a FL280 constraint at neckk and the FMC falsely created one. That made it almost impossible to achieve the naavy window.the argument for the flaw in the SEEVR1 is that neckk's constraint window allows F280 as a legal crossing altitude. Even if the FMC didn't artificially constrain it to F280; the airbus flight computers are frequently satisfied with barely making the highest altitude of a constraint window.either one; or both of these issues could cause the problem that we encountered and even aggressive intervention was insufficient and shouldn't be necessary for normal operations.from our point of view; this looks very similar to the clt ivane approach in it's dysfunctional infancy.thank you and good hunting.
Original NASA ASRS Text
Title: An A321 flight crew; operating in managed descent mode; was cleared to descend via the SEEVR RNAV STAR; FEWWW transition to DFW. As they approached NECKK they noted and accepted the GFMS' intent to cross at FL280 which was the top of the crossing window of between FL280 & FL240. After crossing at FL280 they realized they would be unable to descend to the maximum crossing altitude of FL230 at NAVVY which is only 10NM beyond NECKK. They believe the navigation database does not reflect the charted constraints at NECKK and; in addition; believe the constraint windows between the two fixes are incompatible with aircraft performance if NECKK is crossed at the maximum FL280; providing only 10NM to descend at least 5;000 feet.
Narrative: Descending into DFW via the SEEVR1 arrival; we were given descent to F240 outside of PROWD. We had not yet descended all the way to F240 when we received a frequency change and the next controller cleared us to descend via the SEEVR1; runway 12L. The Captain and First Officer agreed that 7000 feet was the correct setting and the altitude was set. As we continued with the programmed descent we noticed that FL280 was displayed as a temporary constraint in the bottom corner of the primary flight dispaly (PFD). NECKK (our upcoming fix) has constraints of F280-F240 and 290 kt. Since the F280 in the PFD did not violate the NECKK window AND every indicator showed us on profile; we saw no reason to intervene. The aircraft crossed NECKK at F280 and 290 kt. The next fix is NAAVY with constraints of F230-F210 and 290 kt. The aircraft pitched down in an effort to pass through the NAAVY window; but there is only 10 miles between the two fixes and started indicating that it would be high at NAAVY. We extended partial speedbrake and that was insufficient. We then extended full speedbrake and it was still insufficient. I selected open descent and selected a higher speed in an effort to return to the altitude profile. We reached F230 within about 2 miles past NAAVY and restored the automation to the managed mode for the remainder of the profile. This arrival was recently created. We believe that there is either a design flaw in the SEEVR1 or a database error in the FMC.The argument for the database error is that there is not a FL280 constraint at NECKK and the FMC falsely created one. That made it almost impossible to achieve the NAAVY window.The argument for the flaw in the SEEVR1 is that NECKK's constraint window allows F280 as a legal crossing altitude. Even if the FMC didn't artificially constrain it to F280; the airbus flight computers are frequently satisfied with barely making the highest altitude of a constraint window.Either one; or both of these issues could cause the problem that we encountered and even aggressive intervention was insufficient and shouldn't be necessary for normal operations.From our point of view; this looks very similar to the CLT IVANE approach in it's dysfunctional infancy.Thank you and good hunting.
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.