B737 Undifferentiated or Other Model
Flight Crew Air Transport Pilot (ATP)
ATC Issue All Types; Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Clearance; Inflight Event / Encounter CFTT / CFIT
Flight Crew Returned To Clearance
Chart Or Publication; Human Factors
Prior to departure we had had a 6 hour 50 minute ATC delay on the ground. Normal departure with an en route LENDY 6 arrival. After LGA radar vectors then direct KMCHI prior to BUZON 2100 feet was entered into the altitude window. Prior to reaching BUZON we were cleared for the ILS 13L approach and instructed to contact tower. At this time the auto pilot was engaged LNAV VNAV; and approach mode was armed on the MCP (Mode Control Panel). Due to the layout of the Jeppesen 21-3 approach chart we believed we were cleared to descend 2100 feet. Upon contacting tower we were given a low altitude alert. I disconnected the auto pilot and leveled at 2500 feet; at this time the localizer and glide slope captured on the flight director I re-engaged the auto pilot approach mode and gave the aircraft back to the pilot flying. Normal landing and roll out. We heard tower issue a low altitude alert to traffic behind us. Contributing factors - fatigue; high work load; approach chart layout.
Reporter stated the LENDY 6 arrival note was expect radar vectors to final approach course after LGA. Reporter stated they were then cleared to KMCHI and the route segment to BUZON was 2;900 feet; however; they had set 2100 feet which was the altitude for the intermediate fix (TELEX). Reporter stated they did not have time to brief the modified arrival; when switched to tower they were given a low altitude alert about the same time the reporter realized they were below the route segment altitude and he stopped the descent. Reporter stated that on the chart 21-3 the route segment altitude is less obvious than on the NOS chart.
Assigned the LENDY 6 Arrival; which specifically states 'Expect Radar vectors to final approach course after LGA VOR'. Received radar vectors; but at the last minute was cleared direct KMCHI. This clearance is not consistent with the instructions on the arrival. This is an RNAV waypoint stepdown procedure. With little time to brief the approach with this clearance; 2100 feet was set in the MCP. Descent was initiated from 2900 feet after KMCHI. JFK tower notified us of an altitude deviation and the descent was stopped at approximately 2500 ft. A normal approach and landing was executed and we taxied to the ramp. It should be noted that a flight landing behind us got the same altitude deviation alert; indicating the confusion with the arrival and subsequent approach clearance was affecting other flights.
Air Carrier Crew reported on LENDY 6 arrival to Runway 13L at JFK they descended below the route segment altitude and received a low altitude alert from the Tower Controller. Crew leveled off and reported a normal landing.