Date: 201907
Local time of day: 0001-0600
Location: ZZZ.ARTCC, US
Flight conditions: VMC
Weather elements / visibility: 5
Light: Night
Aircraft: B767-300 and 300 ER
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Climb
Airspace: Class A ZZZ
ATC / advisory: Center ZZZ
Reporter organization: Air Carrier
Reporter function: Pilot Not Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine; Flight Crew Instrument
Human factors: Training / Qualification; Time Pressure; Distraction; Communication Breakdown
Second reporter function: Captain; Pilot Flying
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural MEL / CDL
Detector: Automation Aircraft Other Automation; Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Provided Assistance; Flight Crew FLC complied w / Automation / Advisory; Flight Crew Landed in Emergency Condition; Flight Crew Requested ATC Assistance / Clarification
Contributing factors: Human Factors
Primary problem: Human Factors

Narrative: Upon reviewing our paperwork for our IOE flight; several MELs were noted. We discussed each item; but with ZZZ's longer runway NOTAMed closed; our discussion migrated towards the T/R and landing implications. Ultimately agreeing that the Captain would fly the 1st leg into ZZZ. Our review time was cut short due to not receiving our paperwork until approximately 48 minutes prior to our release time (the delay was due to the dispatcher's review of the MEL items. Once in the cockpit; we went over each MEL item; discussing the additional operational requirements for each and pressed on with our preflight and engine starts. Taxi out was normal and Before Takeoff checklist was accomplished - this included selecting the ADP to ON prior to takeoff per the MEL instructions. However; the CENTER ISOLATION switch was not selected OFF. This step in the MEL was missed. (L) Seat takeoff was accomplished along with the ensuing climb and flap retraction on schedule. After flap retraction; the APU was selected OFF and the ADP switch was positioned to AUTO. While climbing through the mid-teens; we noticed the cockpit temperature was rising and little to no cool air was coming through the gaspers. Shortly thereafter; we received a FWD EQPT OVHT alert. The appropriate checklist was run; the light extinguished and remained so; no further action was required. Climbing in the mid/upper 20's; we both noted that the pressurization was working; but appeared to be lagging behind a normal schedule. Approaching FL310 for FL350; we noted the cabin continuing to climb (approx. 6;500 feet) and elected to level off at FL310. After level off; we saw the cabin continuing to climb and immediately requested a descent to FL250 which was immediately approved and executed. While in our descent; the cabin altitude exceeded 10;000 feet. which triggered the CABIN ALTITUDE light and warning. We donned our masks and established crew comms; per the AOM and requested a continued descent to 10;000 feet. The Captain communicated with OPS and the decision to divert into ZZZ1 was made. [ATC was advised]. While on radar vectors; the Captain turned on the APU per the MEL. The; landing and normal shutdown were accomplished without further incident. While discussing the incident with Maintenance in ZZZ1; it was theorized that not placing the ADP in the OFF position; combined with not selecting the CENTER ISOLATION OFF caused reduced flow to the pack and resulted in the pressurization issue. An engine run and test of this proved correct. The appropriate maintenance entries were made and the plane released by Maintenance. After a lengthy review of the MEL Operational Requirements; we flew the jet back to ZZZ2 without incident.Flight crew misread the MEL operational requirements which lead to 'switchology' errors causing the pressurization issue.Briefing time significantly reduced due to late delivery of flight release paperwork. MEL does NOT clearly state to select the ADP to OFF. It is implied; but not plainly stated. MEL placard location - not intuitive to the MEL itself (switch positions. Each MEL item MUST be thoroughly reviewed. Its operational requirements and any potential implications must be noted; briefed and understood. Don't let a departure time compromise our safe habit patterns and practices.


Second narrative: [Report narrative contained no additional information.]


Synopsis: B767-300 flight crew reported they created the pressurization problem by not following the procedures as published in the MEL.