Date: 201501
Local time of day: 0001-0600
Location: ZZZ.TRACON, US
Flight conditions: VMC
Aircraft: B777 Undifferentiated or Other Model
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Initial Approach
Airspace: Class B ZZZ
Aircraft component: MCP
Component problem: Improperly Operated
Reporter organization: Air Carrier
Reporter function: Pilot Flying; First Officer
Human factors: Training / Qualification; Situational Awareness; Fatigue
Second reporter function: Pilot Not Flying; Captain
Anomaly: Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Clearance; Inflight Event / Encounter Unstabilized Approach; Inflight Event / Encounter CFTT / CFIT
Detector: Person Air Traffic Control; Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Issued Advisory / Alert; Flight Crew Became Reoriented
Contributing factors: Human Factors
Primary problem: Human Factors

Narrative: I was the pilot flying; the Captain was the pilot monitoring  After briefing the approach for 36L; with my concurrence; our approach was changed to 36R and we were issued a vector to intercept the Final Approach course; though not cleared for the approach   I initially misunderstood these instructions and wanted to hit the approach arm button; but Captain explained that we should arm the Localizer only in order to prevent an erroneous descent before intercepting the glide slope   As a consequence of this sound advice; I completely forgot to arm the Approach mode when the Final Controller issued the 'Cleared for the ILS 36R' instructions  I don't think I heard the approach clearance - as I know I didn't acknowledge it at the time   This failure on my part went unrecognized by me; though I could see that we were going above glide slope - after I had put the gear down; slowed down; selected final flaps and was completely configured but was also completely confounded as to why the airplane wasn't descending! I got some guidance from the Captain and was descending towards the glide slope but not as quickly as was required to meet the stabilized approach criteria. Around 1;500 feet AGL; the Captain announced that he had the airplane; clicked off the autopilot and descended towards the glide slope   At around 1;200feet AGL; we simultaneously broke out of the clouds in to VMC conditions and passed through the glide slope while the Captain re-engaged the Autopilot; rearmed the Approach mode and offered me the flight controls   With the runway in sight; I took control of the airplane and leveled off as we were slightly below the VASI; and at the same time; the Control Tower announced that we were below glide slope and they had a low altitude alert on our approach.  I then flew the VASI glide slope indications to a normal; uneventful landing  We talked/debriefed at the gate; and I've had some time to reflect on what I did/didn't do   What I learned and will do from now on; is to announce out loud as soon as I am confused   I thought the Approach Mode was engaged and would have sworn to it!  My experience level wasn't enough to see my mistake and correct it before the Captain had to intervene   Ultimately; I'm certain we were safe and had the option to go around and I will chalk this approach lesson up to one that I can learn from but not repeat! When in doubt of your own actions or the actions of your fellow crew members:  say so out loud!  Never hesitate to speak up when your comfort level has been exceeded.


Second narrative: I was the Captain and pilot monitoring. The First Officer (FO) has very low time in the right seat of the 777 and is apparently unused to flying long-haul all-nighters; so it is natural that he was having a little trouble keeping up with the rapidly changing nature of this particular approach. Our runway was changed; 'with our approval'; from 36L to 36R; then in quick succession we were cleared direct to the ZZZ fix; then cleared down to 3;000 feet; then given a right turn to intercept the LOC just outside the ZZZ fix. At this point there was some confusion about whether we had been cleared for the approach; with the FO thinking we were; though we were not yet; and wanting to arm approach mode this resulted in a brief discussion; followed shortly by another one about whether or not he was required to extend the centerline from the FAF. At about this time; I mentioned that we were getting close to the final approach segment and ought to start slowing and configuring.  During this time we were cleared for the approach; but the FO did not mentally register this so he did not then arm Approach Mode to permit intercepting the glideslope (GS). This resulted in us remaining at 3;000 feet in altitude hold mode as we passed through the GS.  The Relief Officer (FB) and I were making suggestions to help him; but I now believe we might inadvertently have been distracting him; making it more difficult for him to get his situational awareness back. As a result; we were coming down slowly; still well above the GS; and I could see that at the current rate we would not get down to it before having to go around. Fortunately; we broke out of the clouds between 1;200 feet and 1;100 feet AGL and were in visual conditions for the rest of the approach and landing; so I realized we had brief window in which to get down to the GS before reaching the required stabilized approach minimum altitude of 500 feet for visual conditions. Otherwise we would have executed a missed approach at 1;000 feet; as is required in IMC. Therefore I briefly took control of the aircraft; disconnected the autopilot; and established a higher rate of descent for a few seconds to get us back to a position where we could be fully stabilized and on the proper visual descent path by 500 feet.  Then I reconnected the autopilot; armed approach mode; and returned control to the FO. Immediately after this; the tower called to relay that they were receiving a low altitude alert on us and to check our instruments. I responded that we were visual. The FO completed the approach and landing in an excellent manner.We conducted an extensive and very constructive debrief in the cockpit after completing the parking checklist; and we agreed that since no regulations had been violated; and the operation was never unsafe; that a report would not be necessary.  However; I was advised this afternoon that it might be a good idea to file one anyway just in case there were any questions about what had happened; so here it is.  Would I do anything differently if presented with a similar situation? Yes; absolutely  I had been allowing the FO to dig himself a hole so that he could better learn from the experience; but 'though that was very valuable once to me as an FO myself'; I shouldn't expect it to be the best method of learning for everyone.  And anyway; I let the hole get too deep before stepping in and taking control.  In the future; I will be more strongly directive earlier in the situation; take control sooner if necessary; and rely much more on the debrief for teaching.


Synopsis: B777 flight crew describes an un-stabilized approach caused in part by fatigue and very low time in the seat by the First Officer and the Captain allowing the First Officer to get a little too far behind before taking over.