Date: 201512
Local time of day: 0601-1200
Location: CYHZ.Tower, NS
Aircraft component: Radio Altimeter
Component problem: Failed
Reporter organization: Air Carrier
Reporter function: Pilot Flying; First Officer
Human factors: Situational Awareness; Distraction
Second reporter function: Captain; Pilot Not Flying
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter CFTT / CFIT; Inflight Event / Encounter Unstabilized Approach; Inflight Event / Encounter Weather / Turbulence
Detector: Automation Aircraft Terrain Warning; Person Flight Crew
When detected: In-flight
Result: Flight Crew Took Evasive Action; Flight Crew Became Reoriented; Flight Crew Executed Go Around / Missed Approach
Contributing factors: Weather; Human Factors; Aircraft
Primary problem: Human Factors

Narrative: The weather conditions at YHZ warranted an ILS Cat II approach. The Captain and I completed the appropriate brief and preparations (including plans stated; threat identification and full Cat II brief) particularly early so as to be as prepared as possible ahead of time. We agreed that we would configure the aircraft early so as to ensure a stable approach and did so successfully. During the approach (Inside FAF); I noticed the 'RA' comparator flag on my PFD; the disappearance of the radio altitude indication on my PFD as well as the CAT2 green indication turn to amber; so I was about to initiate a go-around when; at the same moment; a strong wind gust suddenly pushed the aircraft above the glideslope and increased the airspeed. The autopilot pitched the nose down very dramatically to try and recapture the glideslope; and immediately triggered the SINK RATE and GLIDESLOPE EGPWS warning. I immediately disconnected the Autopilot and initiated a go-around. Although I pressed the go-around buttons on the thrust lever the Flight Mode Annunciator never changed to the GA vertical mode. The captain informed me of that; so I pressed them again and it successfully switched to the GA mode. This event complemented the CatII system failure and hazardous weather conditions to create enough of a distraction to cause me to have a delayed sufficient pitch input to finally reach a positive climb rate. The EGPWS then triggered the TOO LOW TERRAIN or TOO LOW PULL UP annunciation. By that time I had already reached a positive climb rate and we executed a go-around. In the meantime; the weather conditions had increased to Cat1 standards; so we conducted a Monitored ILS Cat1 approach to land in YHZ.Threats: Poor weather conditions; Radio Altimeter failure inside the FAF; execution of an infrequent go-around maneuver.Errors: I did not react as quickly as I wanted to during the go-around maneuver. I momentarily lost situational awareness due to the multiple distractors and the speed at which everything happened together and neglected to verify the GA vertical mode activation and delayed setting the pitch to 10 degrees as one should do during a go-around.UAS: Aircraft below glideslope and subsequent EGPWS activation.I will make sure to always fly the aircraft first. I have had an instance in recurrent training where; despite pressing the GA buttons; the sub-mode fails to activate; and the most important thing was to make sure the nose is brought up FIRST and then add max thrust so as to initiate a climb immediately instead of speeding up while still descending. Although the above description of the sequence of events is a paragraph long; it all happened in the blink of an eye. The autopilot pitched down so dramatically that the normally sequential EGPWS warnings seemed to all trigger at the same time. This is why it is essential to remember the training and procedures. I realized today that anytime we are flying an approach - especially ones in such poor weather conditions - I need to mentally prepare for the eventuality of a go-around and actually run through the sequence in my mind. Anticipation is essential as opposed to reaction where the mere fact that we are caught off guard can add a split-second delay that could cause a significantly different outcome.


Second narrative: We began the go around call outs and he added max thrust and we retracted to flaps 9; however we were still sinking and accelerating when I noticed the aircraft was not in Go Around mode. I informed the FO of this; told him to pull the nose up and I reached down and activated the go around mode since he was focused on hand flying. He pulled the nose up we started to climb so I retracted the gear finished the call outs and we executed the missed approach.


Synopsis: EMB-145LR flight crew reported receiving a GPWS terrain warning on approach into CYHZ after radio altimeter failure and wind gusts affected the approach. A go-around was executed.