Date: 201205
Local time of day: 0601-1200
Location: SFO.Airport, CA
Flight conditions: Mixed
Light: Daylight
Aircraft: B737-500
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Flight phase: Initial Approach
Airspace: Class B SFO
ATC / advisory: TRACON NCT
Aircraft component: FMS/FMC
Component problem: Improperly Operated; Design
Reporter organization: Air Carrier
Reporter function: Captain
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Second reporter function: Pilot Not Flying; First Officer
Anomaly: Conflict Airborne Conflict; Deviation - Altitude Overshoot; Deviation - Speed All Types; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter CFTT / CFIT
Detector: Automation Air Traffic Control; Person Air Traffic Control; Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Issued Advisory / Alert; Air Traffic Control Issued New Clearance; Flight Crew Became Reoriented
Contributing factors: Procedure; Weather; Human Factors; Aircraft; Environment - Non Weather Related
Primary problem: Aircraft

Narrative: A disaster!Arriving in SFO we were cleared for the TIPTOE [Charted] Visual Approach to Runway 28L--with another air carrier aircraft on the FMS BRIDGE Visual to 28R--and were flying a -500 with round dials; of course. We had programmed the TIPTOE Visual fixes in the FMS and were flying in LNAV with 1;900 MSL set in the Altitude window. Aircraft turned to a 310 heading in LNAV at OAK 151/14.0; per the arrival. I selected VOR/LOC and dialed in zero feet with the runway in sight. Shortly thereafter; WE LOST VISUAL TO THE RUNWAY DUE TO A LOW SCUD CEILING. At the same time; VOR/LOC was NOT armed because our [FMS NAV MODE] switches were still in LNAV. I raised the switch and re-engaged VOR/LOC on the MCP; but we had [already] blown through the LOC course; so we were not re-intercepting. We were also below 1;900 MSL so we did not capture and level. I had to hand-fly the aircraft back to the left to rejoin the Localizer. The aircraft was still descending until we leveled at 1;100 MSL. At that time we were ten knots below the minimum speed for our flaps 5 setting and we could not see the bridge or the runway anymore. We were a conflict with the 28R aircraft; probably right underneath him; at which time we were given a low altitude alert by Approach Control. It was a disastrous approach; salvaged to an uneventful landing.Not having glass displays makes this a highly complicated maneuver with nothing to help with situational awareness; an LNAV/VNAV initial routing to a visual maneuver to a localizer approach. There are way too many switches and buttons that have to be engaged at exactly the right time for this to work. I consider myself a competent pilot; but this went from a perfectly briefed and set up arrival to a disaster in about 60 seconds. Seriously; we were not expecting to lose the visual to the runway; and our instrumentation is poor at handling this type of information overload.


Second narrative: Losing sight of the runway on a technically difficult approach like the TIPTOE can prove challenging. The Classic aircraft's gauges aren't the best for situational awareness. Forgetting to flip the switch out of NAV is a common mistake. It seems the approaches to our airports are getting more complex; however; our Classic fleet's instrumentation isn't keeping up.


Synopsis: When the pilot flying inadvertently failed to select the appropriate nav modes; a B737-500; equipped with a single FMS and without a CRT map display; failed to comply with track; altitude and minimum configuration airspeed constraints while assigned the TIPTOE CHARTED VISUAL APPROACH to Runway 28L at SFO. They had been cleared to fly the visual procedure side by side with another air carrier aircraft flying the QUIET BRIDGE CHARTED VISUAL to Runway 28R. The reporters' resultant flight path went through the extended centerline of 28L (separated by only 750 FT from 28R) and their descent prior to receipt of a low altitude alert from Approach Control was about 800 FT below their charted 1;900 crossing at BRIJJ. Both pilots stressed the inadequacy of the non-glass single FMS equipment for terminal navigation; particularly with respect to closely spaced parallel approaches which require side by side aircraft to join up from converging lateral tracks.