B737-300
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 213
Confusion
ATC Issue All Types; Aircraft Equipment Problem Less Severe; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Became Reoriented
Procedure; Aircraft
This is in reference to a situation that caught us completely off guard and I'm sure is one that will be replicated if not addressed in some way. We departed PHX from Runway 7L on the IZZZO 3 Departure which was programmed correctly and initially had no discontinuities or issues with navigation. Shortly after checking-in with Departure Control we were cleared to climb to FL230 (I think) and told to delete the speed restrictions on the departure (I'm sure). The only speed restriction on the departure is at MASVE which is MAX 210 and at or above 7;000 feet. I was the Pilot Monitoring (PM) and the Pilot Flying (PF) was hand flying so he directed me to delete the speed at MASVE. Because I did not want to delete the altitude restriction I elected to change the speed to 250 knots at MASVE and retained the altitude restriction. Almost immediately we got a route discontinuity after FUTER with the appropriate warning. Unfortunately we were rapidly approaching FUTER and being in an older model aircraft with no moving map display; this was an attention getter. At about one mile before FUTER; I reselected AZCRD (the next fix) and put it on the top LSK and executed it. The First Officer (FO) hand flew the new course to AZCRD which the FMC was set to bypass and then it switched guidance rapidly to USEYE as it is only 3.1 miles from AZCRD. The distance from USEYE to MASVE is even less (2.1 miles) and a much larger turn and the guidance on the HSI didn't change directing the turn until late. With no pink line to follow we were late turning and overshot the course to KEENS by about a quarter dot. ATC never mentioned anything and as far as we could tell we maintained the courses within limits while we wrestled the computer. After MASVE everything returned to normal and the rest of the flight was uneventful.A couple of things could be done: 1) Crews should be warned that on this departure; because the first four fixes are so close together (at least in the older models) the airplane cannot accelerate to 250; nor be programmed to do so and still comply with the navigational requirements of the procedure. If you take out the 210 knot restriction by putting in a higher speed you will get a route discontinuity at a very inconvenient time. I'm sure if you delete the whole restriction at MASVE and then reenter just the altitude restriction that the computer will not let you fly faster because it knows it will cause a route disconnect. 2) ATC should not give a speed deletion until after MASVE because I am not sure any aircraft can then comply with route.
While flying the initial segment of the IZZZO 3 RNAV DEP out of PHX; B737 crew was given a 'delete speed restrictions' clearance by Departure Control. Due to the short spacing between the first three fixes on the SID; the crew induced a 'Route Discontinuity' in the current segment of the FMC route immediately after removing the speed restriction on the third fix. Since they were nearly on top the first fix; the crew proceeded direct to the second fix. Crew was unsure if they had followed the correct SID track exactly during the time it took to correctly reprogram the FMC. Crew recommends that ATC not issue this 'delete speed restrictions' clearance until flights are clear of these closely-spaced fixes.