Date: 201505
Local time of day: 0601-1200
Location: ORD.Airport, IL
Aircraft: B737-800
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Taxi
Reporter organization: Air Carrier
Reporter function: Captain
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural MEL / CDL
Detector: Person Flight Crew
When detected: In-flight
Result: General Work Refused
Contributing factors: Human Factors
Primary problem: Human Factors

Narrative: Pilot PushingEnroute to ORD the First Officer and I became aware that we were no longer keeping the aircraft [for the next leg]. We then became aware through our dispatcher that the reason for the switch was an aircraft with an inoperative forward Lavatory (LAV) that had been refused on another trip. That crew was now taking our aircraft and we were scheduled to take theirs. I conferred with my First Officer and we agreed that we would not take an aircraft with an inoperative forward (LAV) on a trip of 775 miles with first class full. For What it's Worth (FWIW) our #1 Flight Attendant agreed with this assessment even though all of us were anxious to get back to base and home after a long 3 day trip. We relayed our decision to our dispatcher enroute and he thanked us for the early heads-up. Later on in flight we reminded our dispatcher and he thanked us again and said the message had been relayed.Upon arrival in ORD and our outbound gate it became readily apparent that we were still scheduled on the same aircraft with the MEL issue. At the gate Chief Pilot came up to me in front of passengers and asked me why I wasn't taking the aircraft. The experience was the worst I have ever had with a Chief. As a former Check Airman and pilot for [company] for almost 30 years I was quite frankly shocked. He was condescending and literally pushing me to take the aircraft. I had to repeat to him more than once that I had made the decision hours earlier and we would need another aircraft. He was very inappropriate and made sure that I knew that we were short aircraft. So; I assume that because we were short aircraft then I should reverse my decision and take the aircraft with the MEL? He also at one point looked at my First Officer and asked if he would operate the trip with this particular airplane. My First Officer said No. I walked away from the inappropriate situation (again-in front of passengers) and that's the last I saw of [him]. Dispatch quickly found us another aircraft and we departed 72 minutes late and arrived 62 minutes late.I obviously have a number of issues here in addition to the inappropriate experience with [the Chief Pilot]. One of them is that not only did someone in dispatch disregard my message enroute about our situation after giving them advance notice of our intentions; but the MEL clearly states in part; '.......(Dispatch will) confer with Captain on flight duration and acceptability if first class or multiple lavatories are inoperative'. This never happened.




Synopsis: A B737-800 Captain reported he felt inappropriate pressure from a Chief Pilot to accept an aircraft he was not comfortable operating with an inoperative forward lavatory.