Narrative:

We have flown 12 legs with an MEL'd FMS. I realize the reaction of anyone over 40 years old to this statement is likely to be; 'so what? We did that for decades.' however; the problem is far more insidious than that. Decades ago; the system was set up to handle traffic in a non-RNAV environment. That is no longer the case. Every flight requires 1 1/2 - 2 1/2 hours to prepare for. Much of this is due to the dispatch department not comprehending that we are not RNAV capable; and not knowing how to file us a route which keeps us within the service volumes of the VOR's throughout our route. It always takes at least 1 and as many as 4 phone calls to dispatch to obtain a compliant flight release. Not once did we receive a first-draft release that was compliant. (And in this case; on leg 11; a NOTAM slipped by us. Although we thought we had received a compliant route from dispatch; we discovered enroute that the mlb VOR had been notamed out of service. The verbiage stating that mlb was out of service was actually at the tail end of multiple lines of verbiage; the first couple lines of which were notams for the localizer back course 27L and ILS or localizer runway 9R approaches. Nowhere was the fact that mlb was out service listed as its own; unique and distinct NOTAM.) once we are done working things out with dispatch; then we can call ATC for clearance. We have to be very careful to make sure that we are issued the final; correct route as agreed to with dispatch; since by then multiple flight plans have been filed with ATC. Of course; that only matters if we are cleared as filed. Clearance delivery routinely issues us clearances which bear no resemblance to the filed flight plan. In these cases; we have to explain that we are not RNAV capable; and must then (again) painstakingly explain how our route must be constructed so that we can actually navigate it on vors only. Once airborne; we ran into problems yet a 3rd time. Controllers almost never notice that we are coded non-RNAV; and repeatedly attempt to give us direct to a fix which we have no way of navigating to; direct to a VOR which is too far away to receive; or a re-route which is again not compliant; or impossible for us to navigate. Even when we are issued and are flying a compliant clearance; the predominant mindset of ATC in an era of GPS/RNAV navigation is that everyone will be within 0.1 miles of centerline. Although we may be perfectly legal being (unwittingly and often undetectably) 2 miles off centerline; the system is no longer designed to accept that kind of slop; and ATC is not tolerant of it; especially in congested areas of the country. In short; telling dispatch; clearance delivery; or center that we are not RNAV capable is equivalent to telling someone that your home phone is on a party line. Most of them barely even understand what you're talking about; and once they do understand; it's almost impossible for them to wrap their brains around it. While not a safety issue; all the confusion and extra time has directly impacted 2 out of 6 flights; one by about 30 minutes and one quite significantly. All of the remaining owner flights would have been impacted except they were all on slides; and the owners did not arrive at the beginning of their slide. At no time were we prepared to depart 30 minutes prior as required by the company. In addition to these issues; flying with an MEL'd FMS poses the following risks: - cannot perform dual verification of waypoints during preflight as required by fom - cannot place a centerline on the mfd for final approach as required by the fom. - Cannot enter basic data for use of vcom on ferry legs as required by fom. - Cannot display airports and navaids on the mfd; substantially reducing enroute situational awareness. - VNAV is unavailable. - Is is unavailable. - ETA to waypoints and to destination have to be manually calculated. - Landing weight must be manually calculated prior to preparing landing performance data. - While attempting to navigate around thunderstorms; without airports and vors displayed on the mfd; we weren't sure where our destination airport was relative to the thunderstorms; in those frequent cases where there was no operational VOR on the field. This made it almost impossible to formulate a plan to deviate left or right of a given build up. While each of these items may be insignificant by itself; in combination they add up to a tremendous increase in task loading; significantly increasing the opportunity for errors to slip by the crew unnoticed. Given the company's proclaimed commitment to reducing navigation errors; it is almost incomprehensible that they would also be perfectly willing to accept all of the additional operational risks associated with an MEL'd FMS; flight after flight; day after day.

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Original NASA ASRS Text

Title: CE560XL flight crew laments flying an aircraft with the FMC on MEL day after day and suggests that the practice should be stopped if schedule reliability and safety is to be maintained.

Narrative: We have flown 12 legs with an MEL'd FMS. I realize the reaction of anyone over 40 years old to this statement is likely to be; 'So what? We did that for decades.' However; the problem is far more insidious than that. Decades ago; the system was set up to handle traffic in a non-RNAV environment. That is no longer the case. Every flight requires 1 1/2 - 2 1/2 hours to prepare for. Much of this is due to the Dispatch department not comprehending that we are not RNAV capable; and not knowing how to file us a route which keeps us within the service volumes of the VOR's throughout our route. It always takes at least 1 and as many as 4 phone calls to Dispatch to obtain a compliant flight release. Not once did we receive a first-draft release that was compliant. (And in this case; on Leg 11; a NOTAM slipped by us. Although we thought we had received a compliant route from Dispatch; we discovered enroute that the MLB VOR had been NOTAMed out of service. The verbiage stating that MLB was out of service was actually at the tail end of multiple lines of verbiage; the first couple lines of which were NOTAMs for the LOC BC 27L and ILS OR LOC RWY 9R approaches. Nowhere was the fact that MLB was out service listed as its own; unique and distinct NOTAM.) Once we are done working things out with Dispatch; then we can call ATC for clearance. We have to be very careful to make sure that we are issued the final; correct route as agreed to with Dispatch; since by then multiple flight plans have been filed with ATC. Of course; that only matters if we are cleared as filed. Clearance Delivery routinely issues us clearances which bear no resemblance to the filed flight plan. In these cases; we have to explain that we are not RNAV capable; and must then (again) painstakingly explain how our route must be constructed so that we can actually navigate it on VORs only. Once airborne; we ran into problems yet a 3rd time. Controllers almost never notice that we are coded non-RNAV; and repeatedly attempt to give us direct to a fix which we have no way of navigating to; direct to a VOR which is too far away to receive; or a re-route which is again not compliant; or impossible for us to navigate. Even when we are issued and are flying a compliant clearance; the predominant mindset of ATC in an era of GPS/RNAV navigation is that everyone will be within 0.1 miles of centerline. Although we may be perfectly legal being (unwittingly and often undetectably) 2 miles off centerline; the system is no longer designed to accept that kind of slop; and ATC is not tolerant of it; especially in congested areas of the country. In short; telling Dispatch; Clearance Delivery; or Center that we are not RNAV capable is equivalent to telling someone that your home phone is on a Party Line. Most of them barely even understand what you're talking about; and once they do understand; it's almost impossible for them to wrap their brains around it. While not a safety issue; all the confusion and extra time has directly impacted 2 out of 6 flights; one by about 30 minutes and one quite significantly. All of the remaining owner flights would have been impacted except they were all on slides; and the owners did not arrive at the beginning of their slide. At no time were we prepared to depart 30 minutes prior as required by the company. In addition to these issues; flying with an MEL'd FMS poses the following risks: - Cannot perform dual verification of waypoints during preflight as required by FOM - Cannot place a centerline on the MFD for final approach as required by the FOM. - Cannot enter basic data for use of vCom on ferry legs as required by FOM. - Cannot display airports and NAVAIDs on the MFD; substantially reducing enroute situational awareness. - VNAV is unavailable. - IS is unavailable. - ETA to waypoints and to destination have to be manually calculated. - Landing weight must be manually calculated prior to preparing landing performance data. - While attempting to navigate around thunderstorms; without airports and VORs displayed on the MFD; we weren't sure where our destination airport was relative to the thunderstorms; in those frequent cases where there was no operational VOR on the field. This made it almost impossible to formulate a plan to deviate left or right of a given build up. While each of these items may be insignificant by itself; in combination they add up to a tremendous increase in task loading; significantly increasing the opportunity for errors to slip by the crew unnoticed. Given the company's proclaimed commitment to reducing navigation errors; it is almost incomprehensible that they would also be perfectly willing to accept all of the additional operational risks associated with an MEL'd FMS; flight after flight; day after day.

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.