Date: 201808
Local time of day: 1801-2400
Location: ZZZ.ARTCC, US
Flight conditions: VMC
Aircraft: B747 Undifferentiated or Other Model
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Cargo / Freight / Delivery
Flight phase: Climb
Aircraft component: Landing Gear
Component problem: Improperly Operated
Reporter organization: Air Carrier
Reporter function: First Officer; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Communication Breakdown; Situational Awareness
Second reporter function: Pilot Not Flying; Captain
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Became Reoriented; Flight Crew Overcame Equipment Problem
Contributing factors: Human Factors; Procedure; Aircraft
Primary problem: Procedure

Narrative: Between scheduled days off; a short medical issue; and sitting R1 waiting for an assignment; I'd been off duty for 2-3 weeks prior to this event. Additionally; due to heavy crew flights I hadn't been up front for a departure in almost a month. Prior to the flight I realized I wasn't the most current; and thus spent some time trying to mentally prepare. When I reported for duty I felt well rested and mentally prepared.Preflight was uneventful; we did not rush; and we had a good; thorough; and interactive briefing. During the briefing; I identified that my time away from work was one of several potential threats and asked the Captain (CA) to keep an close eye on me. Taxi out and the initial take off run were also uneventful. During the takeoff roll the CA commented that the nose seemed lighter than he expected. I agreed and he asked me to be careful and rotate a little slow as a precaution. When the CA called Vr I rotated carefully (only slightly slower than normal) and we had an uneventful liftoff; but because of this I think I may have had slight tunnel vision on the rotation process. We were just off the ground when ATC issued the hand off to departure; who issued several heading and altitude clearances as we climbed. We were not overly busy; but there wasn't a lot of extra time either for the first 3 to 5 thousand feet. Looking back I'm not sure whether the 'positive climb' callout wasn't made; I missed it; or I actually called 'gear up' and the CA missed that callout. Either way; we missed getting the gear up at the proper time and ended up climbing out for some time with the gear in the down and locked position. As we continued climbing out; we retracted the flaps on schedule but the gear remained down. After the flaps were up; the aircraft continued to buffet like the flaps were still out. Although I think I mentally attributed this to turbulence; which seemed reasonable given the windy conditions at the surface. Also during climb out the CA made a comment that climb performance wasn't very good with Climb 2 (which is what we were using). Although this should have been yet another red flag that something wasn't right; given that the CA seemed to state with confidence that the climb rate was due to Climb 2 (which I don't use very much) I didn't question him and merely accepted that the less than stellar climb was due to the derate. As we passed through 10;000' I called for the After Takeoff checklist; as I was calling for the checklist I heard the CA ask if I wanted the gear up. It was at this point that I finally realized what was going on. I first checked to make sure the speed was acceptable for retraction; it was because we were just barely starting to accelerate from 250 KIAS at this point; and called for gear up. I made sure we maintained less than 270 KIAS until the gear had finished retracting. We completed the After Takeoff checklist and the rest of the flight was uneventful. When the gear was up the buffet stopped and I realized that it wasn't turbulence I had been feeling after all. After we reached cruise the CA and I discussed what had happened. It was then that the CA told me he was probably more fatigued than he originally realized. I've never made this mistake before; and I struggled to figure out how I could have done something so stupid as to forget the gear. It was around this time that I realized I probably didn't have my head in the game quite as much as I thought; because I completely missed a lot of red flags that something wasn't right. This would have been a perfect time to have someone in the observer's seat to keep us in line. Also; if the after first flap retraction flow had been done; it would have caught this a lot earlier; but I think we were distracted with ATC instructions when that should have happened. I also realize that we got lucky here. There was very little terrain in the area and we were not overly heavy. If we had made this mistake when we were heavy and/or coming out of an airport with significant terrain this could have had terrible consequences. It would be good to sit down and chair fly a couple of times before returning to work after a break in order to help be a little more current and up to speed for the flight. Getting refreshed with the flows might also help with avoiding errors from distraction.


Second narrative: After a series of day night sleep cycle reversals we failed to raise the landing gear immediately after takeoff. During the takeoff roll we both noticed that the aircraft seemed light on the nose. I recommended a careful rotation in case the weight and balance was erroneous.After a slightly slow rotation we received an immediate frequency change and the positive climb callout was not made nor was the gear up command. During our initial climb we both remarked at the slow climb rate (approximately 1200-1300 FPM). We had two further frequency changes in short succession. It was only after climbing for several thousand feet that we realized the gear was still down. We immediately raised the gear and noted that we had not exceeded the airspeed limitation.I believe a major contributor to this event was cumulative fatigue from several consecutive diurnal cycle reversals and short layovers.This event occurred on the fifth calendar day on duty during my sixth duty period. While looking at the individual duty periods each one was legal under part 121 but they would not have been under part 117. I believe that due to the insidious onset of fatigue I was not aware of how tired I was. Having 6 duty periods in 5 days was definitely a contributing factor to that fatigue and should never be scheduled.


Synopsis: A B747 flight crew reported that they failed to raise the landing gear after takeoff.