Medium Transport
Flight Crew Air Transport Pilot (ATP)
Other / Unknown
Conflict Airborne Conflict; Deviation - Altitude Excursion From Assigned Altitude
Flight Crew FLC complied w / Automation / Advisory; Flight Crew Took Evasive Action
Airspace Structure; Human Factors
Flight was to Kahului. We were given a descent clearance to 8;000. At approximately 9;500 we switched controllers. We called the field in sight and then were told to maintain 9;000. As we were leveling at 9;000 we received a TCAS RA Command. 'Descend; Descend.' Pilot flying disconnected the autopilot and began descending; the command was a full down command. As soon as the pilot flying started to descend we received a 'Climb; Climb' command. This was also a full scale command. The pilot flying started to climb. As soon as he started to climb we received a 'Monitor Vertical Speed' command. During this event we initially did not see the aircraft on our TCAS. Shortly after we saw the TCAS traffic; it was indicating that it was headed towards us and at our altitude. The highest the TCAS traffic climbed to was 300 feet above our altitude (9;000). I happened to look out the window and was the aircraft very close heading for us and then it made a steep turn to the left (our right). We recognized it as being a Cessna Caravan. They looked to be approximately 100 yards away from us. If they did not turn it would have been a midair collision. I asked the Controller how this had happened. He said that the Caravan was VFR traffic and that they were only supposed to be climbing to 8;500. According to our TCAS they climbed through our altitude to approximately 9;300. I checked with the flight attendants to see if the passengers were ok (they were) and to let them know what happened. We proceeded to our destination. I think it occurred because the other aircraft (Caravan) deviated from their altitude. They had no idea that we were there. Because of this ATC did not know what they were doing until we almost had a mid air collision. Pilot flying followed the TCAS commands until we were clear of the conflict. First I think we were lucky to have our TCAS. I think without it we may have collided. This has happened many times to me personally with these Cessna Caravan VFR traffic. I have had to deviate many times because they do not talk to anyone. They fly into departure corridors and depart in the opposite direction as inbound traffic. I feel the only way to be safe from this is for them to be IFR. That way everyone will know what their intentions are and we will have the proper separation. I feel ATC is doing the best they can; however the unknown is these VFR traffic that fly into IFR airspace. Something needs to be done before we have an accident.
We were on descent into Kahului; going direct to MAKEN. We were (best guess here) 5 miles from MAKEN. Center had given us pilot's discretion to 8;000 FT. Passing through 9;500 we reported the field in sight for a visual approach. Center responded with 'maintain 9;000 FT'. We leveled at 9;000 and then the TCAS showed a target climbing and heading towards us. We were unable to visually see the other aircraft. We watched the target continue the climb and head right towards us. We first received a TA immediately followed by a RA commanding a maximum rate descent. I was ready to comply and did so immediately. Upon arriving at the green indices for a descent rate of 4;000 FPM down; the TCAS changed its mind and commanded a 4;000 FPM climb. About the time I arrived at the green band for the climb we received a 'monitor vertical speed' and the 'clear of conflict'. At the same time I heard 'monitor vertical speed' I saw the other aircraft at my 1-2 o'clock and slightly above us. He sure seemed close. Because he was in a left turn and above us I was able to see the other plane's underside. The Captain reported both the RA descent and RA climb. About the same time the event was over; HCF asked us to switch to OGG Approach. Before switching the Captain asked how that had happened and HCF said the other aircraft was supposed to be at 8;500 FT.I think there are several reasons this event happened: The TCAS system in our aircraft does not show traffic until they are within 2;800 FT of our altitude. If the TCAS system showed traffic further from our altitude we would have had more notice of his approach. I don't believe the Caravans that fly around here have TCAS that will coordinate with our TCAS on escape actions. I think that's why we had 2 different resolutions. [The Caravans] fly VFR and therefore are often in the same airspace that we are but there is no required ATC separation and sometimes no ATC communication. I don't know if the other aircraft was in ATC communication or not. Maybe they were on OGG Departure and we were on HCF and ATC was not coordinating well. I'm not sure. HCF quickly changing our altitude clearance (only after communication was initiated by us) indicates to me that they had only just spotted the conflict. That corner of Maui has the convergence of multiple Victor airways. Mixing VFR traffic with the confluence of IFR traffic is a bad idea. Coming in to Maui from Kona and Hilo; I frequently encounter IFR/VFR traffic conflicts with Caravans.
Air Carrier pilots experience a TCAS event at 9;000 FT descending into OGG that initially commands a maximum descent; then reverses and commands a maximum climb. Upon receiving a clear of conflict announcement the traffic is sighted at one to two O'clock and slightly above.