Date: 201210
Local time of day: 1801-2400
Location: TEB.Airport, NJ
Flight conditions: VMC
Light: Daylight
Aircraft: BAe 125 Series 800
Operator: Air Taxi
Operating under: Part 135
Flight plan: IFR
Mission: Passenger
Flight phase: Descent
Airspace: Class E N90
ATC / advisory: TRACON N90
Aircraft component: FMS/FMC
Component problem: Design; Malfunctioning
Reporter organization: Air Taxi
Reporter function: First Officer; Pilot Not Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Human-Machine Interface; Distraction; Communication Breakdown; Workload
Second reporter function: Pilot Flying; Captain
Anomaly: Aircraft Equipment Problem Less Severe; Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
When detected: In-flight
Contributing factors: Aircraft; Chart Or Publication; Procedure
Primary problem: Ambiguous

Narrative: Cleared descend via the JAIKE THREE Arrival. Descent to 11;000 FT begun before ILENE; ILENE has a mandatory 13;000 FT altitude. Two equipment problems; a similar aircraft call sign; an extremely busy frequency and multiple speed change requests contributed to the deviation. The two equipment problems: The FMS would not stay in the full performance mode; periodically dropping into current mode causing the VNAV to be unavailable; therefore we did not have VNAV available for this procedure. Second; the intercom was intermittent from the left seat to the right. I could not hear the Captain much of the time; as if the squelch was not sensitive enough. These two items increased our workload. Three minutes ahead of us was another aircraft on the same path a while. The Controller before this one had struggled twice with getting the call signs correct; and I took one call of theirs earlier; again; increasing attention required and stress. Finally we had approximately 5 speed change requests in the 2-3 minutes before the altitude deviation from 280; down to 250; up to 290 and back to 250. The deviation occurred shortly after crossing JAIKE at the 13;000 FT mandatory altitude. We were calculating the descent rate needed to reach WACKI at 11;000; and has just been given another airspeed reduction from 290 to 250. The pilot flying called for 11;000 in the altitude alerter; which I did (and should have questioned; but did not.) The pilot flying started down and asked me to verify the 250 speed request. When I asked the Controller if he wanted 250 at WACKI the Controller said yes; and that we should not have started down yet. The pilot flying and I immediately recognized the error and the pilot flying called ATC and asked if we should go back up; he said no; the current altitude was OK. We were 600 FT low about 3-4 miles early. Having two fixes with 13;000 FT mandatory altitudes 26 miles apart; followed by a descent to 11;000 in 8 miles contributed as well. We were simply overloaded with too many numbers and calculations happening simultaneously. I was very frustrated with myself for not catching this error before it happened. While trying to find the Live ATC feed to hear for review and clarity I came across this article published in July. It turns out this is a VERY common mistake. 'TRACON is concerned over the growing number of deviations from the published altitudes on the JAIKE Three. Failure to comply with these published altitude restrictions will result in loss of separation between adjacent traffic thereby creating a significant safety hazard. During a recent controller shift; 4 out of 7 airplanes (57%) failed to comply with the 'at' 13;000 restriction at ILENE (i.e. descended early after passing JAIKE at 13;000 FT.' Knowing other pilots also make this mistake is not an excuse for me to make it. However; if MOST pilots are making the exact same mistake in the same place this is a flawed procedure. I hope this report can contribute to changes.


Second narrative: I must say I have experienced more avionic failures/anomaly's in the last 10 months of flying Honeywell than previous in my total career. These old avionics are unreliable and combined with our 'new' flight crew members who are not adequately trained creates together a very challenging situation. I suggest we either segregate Honeywell/Collins flight crews (higher level of safety) or if we must cross train; all IOE pilots should receive training in both types and then each pilot should be pro-actively rotated between avionic types.


Synopsis: A BAE-125-850XP; with an inoperative VNAV FMS mode; descended 500 FT before the 13;000 FT JAIKE 3 ILENE constraint before ATC and crew saw the descent to 11;000 FT begin.