Date: 201510
Local time of day: 1201-1800
Location: DFW.Airport, TX
Flight conditions: IMC
Weather elements / visibility: Thunderstorm; Turbulence
Light: Dusk
Aircraft: Regional Jet 900 (CRJ900)
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Descent
Airspace: Class E D10
ATC / advisory: TRACON D10
Aircraft component: MCP
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Pilot Not Flying; First Officer
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Situational Awareness
Second reporter function: Pilot Flying; Captain
Anomaly: ATC Issue All Types; Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Issued Advisory / Alert; Air Traffic Control Issued New Clearance; Flight Crew FLC Overrode Automation; Flight Crew Requested ATC Assistance / Clarification; General Maintenance Action
Contributing factors: Aircraft; MEL; Procedure
Primary problem: MEL

Narrative: After pre-flight we discussed the maintenance issues; one of which was MEL 22-10-02 which is in reference to the 'heading bug' being inoperative with the autopilot. We discussed the MEL which stated that the aircraft was airworthy and capable of operating in RVSM and RNAV scenarios. During the flight we received clearance via the SOCKK TWO RNAV arrival. Before reaching GUTZZ intersection we received direct KIILO; and approximately 20 NM from KIILO we received a 'descend via' clearance for the SOCKK TWO arrival. Due to the speed restriction given to us of 270 and the late descend via clearance we determined that we 'might be a little high' at KIILO. I informed ATC (Fort Worth center) and we received clearance to be high at KIILO as long as we maintained 270 KTS. We maintained 270 and made the altitudes listed at KIILO. It is around this time that the Fort Worth center controller gave us a left turn for spacing. The captain then advised the controller of our current MEL and that we would have to disconnect the autopilot to make the turn; and therefore be unable to continue the RNAV arrival. The Fort Worth Controller then cleared us to stay on the arrival and maintain 230 KTS. We were then handed off the Regional Approach control. We checked in with Regional Approach control and were issued a speed reduction to 210 KTS; a descent to 6;000 MSL and a left turn. The captain then reiterated our MEL and that if we took the turn we would have to disconnect the autopilot and would be unable to continue the RNAV arrival. The controller acknowledged the issue; and issued the turn again; at which point we immediately disconnected the autopilot and made the turn to the assigned heading. Shortly after which the Regional Approach controller advised us of a 'Possible Pilot Deviation' and we copied a phone number down. We complied with each altitude and speed restriction given to us during the flight and landed the aircraft without further incident.I believe this was a miscommunication/ misunderstanding with Air Traffic Control and ourselves. Better communication of current aircraft operational limitations with Air Traffic Control; and possibly more understanding of company operational limitations by Air Traffic Control could easily prevent this situation from reoccurring.


Second narrative: WE were descending on the SOCKK2 into DFW and was cleared to KIILO intersection with altitude relief until BOOVE; but given 280 knots or less and was doing 270 knots. At some point around KYSSS intersection ATC asked us to make a left for spacing. My first officer initially responded 'unable'. I took the radio call and explained that we have an MEL that is operationally limiting the aircraft. Advised that we can take the turn; but that would require the autopilot to come off and then we would no longer be able to continue on the RNAV arrival. ATC then advised to stay on the SOCKK2 and slow to 230 knots and we complied. Next controller issued a left to us prior to BOOVE intersection. Advised controller of same issue and he stated he understood and needed the turn for spacing. Autopilot was turned off; made turn and continued with vectors. We were advised by ATC to copy a phone number for pilot deviation. Once at the gate; I called the number and was advised they will be investigating the incident. I stated my case with the person on the phone and asked for all tapes to be saved and a copy for myself. Was given a phone number to their Quality Assurance manager and told he would be in touch with me.This was due to a poor MEL. The write up was for the heading bug and the MEL was for flight director modes. Poor guidelines given on the MEL. Please refer to MEL 22-10-02. I did not know or understand what this MEL was actually referencing by the MEL itself. Once airborne we needed a vector for weather and put the aircraft in Heading mode and realized that the Heading bug was not functioning properly. We could not turn the aircraft to a specific head using the Heading bug. In no way did this MEL address this issue. Once on the ground I called MX and advised that this aircraft should not be flown until fixed and they agreed.


Synopsis: CRJ900 Flight Crew reported being dispatched with MEL 22-10-02 for the heading bug not controlling the autopilot. This became an issue during the arrival when ATC issued a heading and the crew informed them the autopilot must be turned off to comply and they could no longer fly the RNAV arrival. ATC issued the heading again then asked the crew to copy a phone number for a possible pilot deviation.