Narrative:

I have only been on this airplane for 3 months, but it has become fairly clear that this 'new generation' aircraft has several FMS design deficiencies. Most of them can be summed up with one observation. Extreme reliance on multi-function controls. The worst is the heading select/heading hold switch. I have seen more human factor errors committed with this switch, even with pilots with 5-8 yrs of experience on this aircraft. First of all it incorporates a slow/fast selection that requires a pilot to push the knob into a mid/non-detented position to effect a fast selection. Next it defies convention by requiring the pilot to pull out on the switch from its normal position to get the aircraft to immediately turn to the selected heading. To get the aircraft to hold its heading you have to push on the switch (beyond the fast slow position). The next 'bad' switch is the altitude selector. Someone decided that most of the time pilots select altitude in 1000 ft increments, so they designed a system based on that premise. Knowing that mdp or decision ht on approachs were not in 1000 ft increments, they put in another function in the switch where the pilot had to push in the switch to another non-detented position to access 100 ft selections. There was no accommodation for 10 ft increments. The problem comes when you have to do successive stepdown altitudes on a non-precision approach. Altitude selection and accommodation to compensate for the intermediate 100 ft selection position and lack of 10 ft increments becomes a full time occupation. This is during a high workload period. The old one position altitude select switch where the pilot passes through all possible desired altitudes serves the pilot best. With new electronic rather than analog dials maintenance wouldn't be a problem. Callback conversation with reporter revealed the following information: this reporter said that he is in the process of writing his thesis on human factors, and that this aircraft is being used as a representation of a design problem. He complained about the multi-function switches that are not detented. Other pilots had told him that he would get used to the switch operation, but he has witnessed errors in operation by those same pilots. Another problem the reporter alleged was the different approachs to operating the autoflt system. The ground school instructions taught one way of setting up and operating the autoflt system that was used all the way through the simulator, but his line instructors and check pilots told him to use quite a different technique. The reporter said that he has learned to use the system, but he still thinks that it is unfriendly.

Related reports:

Google
 

Original NASA ASRS Text

Title: AN ACR CAPT COMPLAINS ABOUT THE AUTOFLT SYS CTL SWITCHES ON THE MD88, PARTICULARLY THE MULTI-FUNCTION ALT SELECT ALT HOLD SWITCH AND THE HDG SELECT HDG HOLD SWITCH.

Narrative: I HAVE ONLY BEEN ON THIS AIRPLANE FOR 3 MONTHS, BUT IT HAS BECOME FAIRLY CLR THAT THIS 'NEW GENERATION' ACFT HAS SEVERAL FMS DESIGN DEFICIENCIES. MOST OF THEM CAN BE SUMMED UP WITH ONE OBSERVATION. EXTREME RELIANCE ON MULTI-FUNCTION CTLS. THE WORST IS THE HDG SELECT/HDG HOLD SWITCH. I HAVE SEEN MORE HUMAN FACTOR ERRORS COMMITTED WITH THIS SWITCH, EVEN WITH PLTS WITH 5-8 YRS OF EXPERIENCE ON THIS ACFT. FIRST OF ALL IT INCORPORATES A SLOW/FAST SELECTION THAT REQUIRES A PLT TO PUSH THE KNOB INTO A MID/NON-DETENTED POS TO EFFECT A FAST SELECTION. NEXT IT DEFIES CONVENTION BY REQUIRING THE PLT TO PULL OUT ON THE SWITCH FROM ITS NORMAL POS TO GET THE ACFT TO IMMEDIATELY TURN TO THE SELECTED HDG. TO GET THE ACFT TO HOLD ITS HEADING YOU HAVE TO PUSH ON THE SWITCH (BEYOND THE FAST SLOW POS). THE NEXT 'BAD' SWITCH IS THE ALT SELECTOR. SOMEONE DECIDED THAT MOST OF THE TIME PLTS SELECT ALT IN 1000 FT INCREMENTS, SO THEY DESIGNED A SYS BASED ON THAT PREMISE. KNOWING THAT MDP OR DECISION HT ON APCHS WERE NOT IN 1000 FT INCREMENTS, THEY PUT IN ANOTHER FUNCTION IN THE SWITCH WHERE THE PLT HAD TO PUSH IN THE SWITCH TO ANOTHER NON-DETENTED POS TO ACCESS 100 FT SELECTIONS. THERE WAS NO ACCOMMODATION FOR 10 FT INCREMENTS. THE PROB COMES WHEN YOU HAVE TO DO SUCCESSIVE STEPDOWN ALTS ON A NON-PRECISION APCH. ALT SELECTION AND ACCOMMODATION TO COMPENSATE FOR THE INTERMEDIATE 100 FT SELECTION POS AND LACK OF 10 FT INCREMENTS BECOMES A FULL TIME OCCUPATION. THIS IS DURING A HIGH WORKLOAD PERIOD. THE OLD ONE POS ALT SELECT SWITCH WHERE THE PLT PASSES THROUGH ALL POSSIBLE DESIRED ALTS SERVES THE PLT BEST. WITH NEW ELECTRONIC RATHER THAN ANALOG DIALS MAINT WOULDN'T BE A PROB. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THIS RPTR SAID THAT HE IS IN THE PROCESS OF WRITING HIS THESIS ON HUMAN FACTORS, AND THAT THIS ACFT IS BEING USED AS A REPRESENTATION OF A DESIGN PROB. HE COMPLAINED ABOUT THE MULTI-FUNCTION SWITCHES THAT ARE NOT DETENTED. OTHER PLTS HAD TOLD HIM THAT HE WOULD GET USED TO THE SWITCH OP, BUT HE HAS WITNESSED ERRORS IN OP BY THOSE SAME PLTS. ANOTHER PROB THE RPTR ALLEGED WAS THE DIFFERENT APCHS TO OPERATING THE AUTOFLT SYS. THE GND SCHOOL INSTRUCTIONS TAUGHT ONE WAY OF SETTING UP AND OPERATING THE AUTOFLT SYS THAT WAS USED ALL THE WAY THROUGH THE SIMULATOR, BUT HIS LINE INSTRUCTORS AND CHK PLTS TOLD HIM TO USE QUITE A DIFFERENT TECHNIQUE. THE RPTR SAID THAT HE HAS LEARNED TO USE THE SYS, BUT HE STILL THINKS THAT IT IS UNFRIENDLY.

Data retrieved from NASA's ASRS site as of July 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.