B777 Undifferentiated or Other Model
Flight Crew Air Transport Pilot (ATP)
Situational Awareness
Deviation - Altitude Crossing Restriction Not Met; Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Issued Advisory / Alert; Air Traffic Control Issued New Clearance; Flight Crew Became Reoriented
Human Factors
I was an International Relief Officer (IRO) on the flight sitting behind the First Officer (FO). When we transitioned from the STAR to the arrival and cleared for the approach Localizer Directional Aid (LDA) Rwy 30; 4;500 ft was displayed and I assume that the Pilot Flying (PF) must have pushed the ALT button; since the aircraft started to go down to that altitude. The problem was that it was about 2 miles prior to LIMKO (IAF). I stated that we needed to be at 5;000 Ft. until we passed that point; but it was too late since the aircraft was already at 4;500 Ft. The ATC stated that we should have been at 5;000 Ft; but said that we could remain at 4;500 Ft. Since; the visibility is limited from that jumpseat; I did not see how we came to be at 4;500 Ft.; but I went off the voice call outs and thus made the remark that we needed to be at 5;000 Ft; but it was too late.
On the LIMKO1 STAR to LDA 30 TLV; assigned 5;000 Ft. MSL and 210 kts at LIMKO; leveled off at 5;000 MSL prior to LIMKO. ATC cleared us for the LDA 30 approach; I as Pilot Not Flying (PNF); set 4;500 MSL in ALT window (the next lower altitude prior to the approach); VNAV ALT displayed on FMA. Captain as First Officer pressed altitude selector; and we did not monitor the altitude restriction deleted on the FMC from ALT selector button push; subsequently; the aircraft descended to 4;500 MSL prior to LIMKO altitude restriction of 5;000 MSL. ATC noted the deviation from STAR; we acknowledged are current altitude of 4;500 MSL. ATC cleared us to next fix on approach at 4;500 MSL. No further incident noted.
B777 flight crew reports descending below charted altitude on the LIMKO1 arrival to LLBG which is detected by one of the IRO's and ATC but too late to prevent the deviation.