Small Transport; Low Wing; 2 Recip Eng
Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine; Flight Crew Instrument
Flight Crew Last 90 Days 25; Flight Crew Total 5500; Flight Crew Type 2500
Deviation - Altitude Crossing Restriction Not Met; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
General None Reported / Taken
Chart Or Publication; Human Factors
I was being vectored for the approach from the northwest of the airport. I was brought in on a wide downwind and then vectored to the final approach course as would be expected coming from the northeast. I was told to maintain 150 KTS (the PA31 gear speed is 130 KTS and cruise is 160 KTS). I was advised that I would be vectored through the inbound course (60 degrees) for separation and would be turned in from the other side of the course. While being vectored through a course for separation is a fairly common event; it seemed counter intuitive in that I had been asked to keep my speed up to 150 KTS; but I was doing as directed. After flying through the course; I was given a heading of 040 degrees to intercept the inbound course. I was then turned an additional ten degrees to 030 degrees for the intercept and instructed to 'maintain 2;000 FT until established; cleared for the approach.' I intercepted the localizer at 2;000 FT while slowing to gear speed and then intercepted the glideslope and flew the approach. I believe that it was on short final the Tower made a quick comment that I missed the 1;500 FT mandatory altitude at DANDY. In reviewing both Jeppesen and NACO plates; it is more clearly depicted on the Jeppesen plates than on the NACO plate. The Jeppesen plate has a capital lettered notation regarding the 1;500 FT altitude and it appears from the depiction of the descent profile that this fix is below the glideslope. The NACO plate has no such clear notation and it appears on the descent profile depiction that 1;500 FT altitude is on the glide path instead of a step-down. It would seem appropriate for the NACO charts to be adjusted to a notation format for this situation more in tune with what the Jeppesen plate has done to be more clear on this mandatory altitude. A step-down in the descent profile would also have been helpful. The NACO chart clearly is more likely to lead to confusion and excursions from the mandatory altitude. It also seems that setting up a required altitude on an approach that is below the glideslope is a situation likely to cause a problem in a high work load environment. Needless to say; the New Jersey/New York airspace is very busy and complex.
An Air Taxi pilot did not cross the TEB ILS RWY 6 DANDY waypoint at 1;500 FT because he misread the NACO chart plan view graphical formatting which indicated being on glideslope would meet the restriction; when in fact a step down is required.