|37000 Feet||Browse and search NASA's
Aviation Safety Reporting System
|Local Time Of Day||1201 To 1800|
|Locale Reference||airport : mwc|
|Altitude||msl bound lower : 1260|
msl bound upper : 1500
|Controlling Facilities||tracon : mke|
tower : mwc
|Operator||general aviation : personal|
|Make Model Name||Small Transport, Low Wing, 2 Recip Eng|
|Flight Phase||descent : approach|
|Function||flight crew : single pilot|
|Qualification||pilot : instrument|
pilot : commercial
|Experience||flight time last 90 days : 20|
flight time total : 3500
flight time type : 150
|Function||controller : local|
|Qualification||controller : non radar|
|Anomaly||other spatial deviation|
|Independent Detector||atc equipment other atc equipment : unspecified|
|Primary Problem||Flight Crew Human Performance|
|Air Traffic Incident||other|
After a rapid descent, we were cleared for the VOR 4L approach at mwc several mi before phyls FAF. Crossed FAF 40-50' high, which was ok because we planned on a rapid descent after passing FAF to minimum descent altitude. Made positive visual ground contact after several hundred feet of descent from phyls (FAF). Continued descent to minimums and towards runway 4L mwc. Shortly thereafter, received a call from mwc tower that mke approach control had a low altitude alert warning, and the tower gave us a new altimeter setting. We had established our location visually being familiar after 35 yrs of flying from the airport. But, the call was still very distressing and distracting at a time when all efforts should have been directed to flying the airplane and the approach. I believe the altitude alert sounded because the computer calculated our descent profile to dive us into the ground before reaching the runway. I talked to several instrument instrs and they couldn't tell me if the approach control computer was programmed that way. Finally an ATP indicated he heard of several times that it happened, and yes, it was programmed into the computer. I believe the low altitude alert warning is a great safety factor and it is proper to inform the pilot. I think, however, if a low alert is sounded by a steep profile computer calculation on a nonprecision approach, instrument instrs, pilots and students should be made aware of the fact so as not to be distracted trying to figure out why low altitude was called when all the gauges and the approach seem to be going fine. This could be accomplished simply through the various safety notifications and aviation publications, both public and private. Callback conversation with reporter revealed the following: the reporter reiterated that he thought the parameters of the MSAW should be more widely published so that a pilot could anticipate an alert when conducting a steep approach and then not spend too much time worrying about it. He also said that he was depending on his intimate familiarity with the terrain on this approach to help him find the airport.
Original NASA ASRS Text
Title: SMT ACTIVATED THE MSAW WHEN CONDUCTING A STEEP VOR APCH.
Narrative: AFTER A RAPID DSCNT, WE WERE CLRED FOR THE VOR 4L APCH AT MWC SEVERAL MI BEFORE PHYLS FAF. CROSSED FAF 40-50' HIGH, WHICH WAS OK BECAUSE WE PLANNED ON A RAPID DSCNT AFTER PASSING FAF TO MINIMUM DSCNT ALT. MADE POSITIVE VISUAL GND CONTACT AFTER SEVERAL HUNDRED FEET OF DSCNT FROM PHYLS (FAF). CONTINUED DSCNT TO MINIMUMS AND TOWARDS RWY 4L MWC. SHORTLY THEREAFTER, RECEIVED A CALL FROM MWC TWR THAT MKE APCH CTL HAD A LOW ALT ALERT WARNING, AND THE TWR GAVE US A NEW ALTIMETER SETTING. WE HAD ESTABLISHED OUR LOCATION VISUALLY BEING FAMILIAR AFTER 35 YRS OF FLYING FROM THE ARPT. BUT, THE CALL WAS STILL VERY DISTRESSING AND DISTRACTING AT A TIME WHEN ALL EFFORTS SHOULD HAVE BEEN DIRECTED TO FLYING THE AIRPLANE AND THE APCH. I BELIEVE THE ALT ALERT SOUNDED BECAUSE THE COMPUTER CALCULATED OUR DSCNT PROFILE TO DIVE US INTO THE GND BEFORE REACHING THE RWY. I TALKED TO SEVERAL INSTRUMENT INSTRS AND THEY COULDN'T TELL ME IF THE APCH CTL COMPUTER WAS PROGRAMMED THAT WAY. FINALLY AN ATP INDICATED HE HEARD OF SEVERAL TIMES THAT IT HAPPENED, AND YES, IT WAS PROGRAMMED INTO THE COMPUTER. I BELIEVE THE LOW ALT ALERT WARNING IS A GREAT SAFETY FACTOR AND IT IS PROPER TO INFORM THE PLT. I THINK, HOWEVER, IF A LOW ALERT IS SOUNDED BY A STEEP PROFILE COMPUTER CALCULATION ON A NONPRECISION APCH, INSTRUMENT INSTRS, PLTS AND STUDENTS SHOULD BE MADE AWARE OF THE FACT SO AS NOT TO BE DISTRACTED TRYING TO FIGURE OUT WHY LOW ALT WAS CALLED WHEN ALL THE GAUGES AND THE APCH SEEM TO BE GOING FINE. THIS COULD BE ACCOMPLISHED SIMPLY THROUGH THE VARIOUS SAFETY NOTIFICATIONS AND AVIATION PUBLICATIONS, BOTH PUBLIC AND PVT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING: THE RPTR REITERATED THAT HE THOUGHT THE PARAMETERS OF THE MSAW SHOULD BE MORE WIDELY PUBLISHED SO THAT A PLT COULD ANTICIPATE AN ALERT WHEN CONDUCTING A STEEP APCH AND THEN NOT SPEND TOO MUCH TIME WORRYING ABOUT IT. HE ALSO SAID THAT HE WAS DEPENDING ON HIS INTIMATE FAMILIARITY WITH THE TERRAIN ON THIS APCH TO HELP HIM FIND THE ARPT.
Data retrieved from NASA's ASRS site as of August 2007 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.