As a keen spotter back in the days of REAL aircraft, living under the approach to 23, I used to love the 23 landings as I got great views and heard
great sounds (I'd lie awake waiting to hear the regular parade of late night freighters - Balair DC-4 (for Swissair), Aviaco DC-4 (for Iberia) and Air France Breguet Deux Ponts amongst others. I doubt ATC or most pilots were as keen on using 23 and it buggered up the local TV reception!
The PanAm 707 that went to Northolt in error (to get it back out it was stripped of all but the bare essentials and flown out with minimum fuel to get to LHR just 5 crow miles away) was one of a number of aircraft that got LHR 23 and Northolt 26 mixed up. The approaches intersected in the Harrow area and both had similar looking gas holders as visual approach landmarks (near enough) directly under the extended centrelines.
Quite a few pilots lined themselves up nicely on the approach to Northolt in error and had to be shepherded back towards 23 by Heathrow Approach. Eventually the South Harrow gas holder had large NO letters applied and the Southall one had LH painted in large letters with a direction arrow - I believe the LH and arrow are still visible on the Southall tank.
Until about 1970 23 had no ILS so visual and precision radar (now there's a skill!) approaches were the go, often in low cloud base and/or windshear conditions as 23 was only used latterly when approaches to 28s (27s now) were not safe due to crosswinds. There was a great keenness to bust the cloud and become visual as soon as possible by some pilots leading to some interesting issues with the 300 odd foot high Southall gas tank. More than once aircraft had to make sudden detours AROUND the tank which being about 3 miles out was really not a situation they should have been in over the London suburbs! Impressive to see and hear though - memories of an Alitalia DC-8 at about 300 feet and high angle of bank with full power comes to mind!
Also there was a VERY near miss over Harrow in January 1970 when an Indian Air Force Super Constellation (aaah!) apparently tried to go in too low towards Northolt 26 (cloud busting again I suspect) and had to be warned by Northolt GCA that they were in imminent danger of becoming a permanent fixture at Harrow on the Hill so were instructed to make an emergency climbing turn. An Olympic 727 was in cloud on approach to LHR 23 and before Heathrow and Northolt ATCs could co-ordinate any warning the climbing Connie apparently passed so close to the 72 that its full throttle engines could allegedly be heard inside the Boeing! That's
close if true! This incident gets a mention in Hansard -
HEATHROW AIRPORT (SAFETY STANDARDS) (Hansard, 27 January 1970)
To compound the possibilities of this situation a USAF C-54 (piloted by an about to retire General I seem to recall) actually tried to land at the then closed Hendon field (under the approach to Northolt 26) instead of Northolt in the late 60s which would have been er.., 'interesting'.
