British Airways were so concerned about the Category 3 certification, as there were only at that time two or three suitable runways in North America on which it could be fully used. It was pointed out that British Airways had 12 such runways on its domestic network alone, four of them at its main base at Heathrow. In the 1980s and 1990s, there was increasing pressure globally from customer airlines for at least some improvements in low visibility operations; both for flight regularity and from safety considerations. At the same time, it became evident that the requirement for a true zero-visibility operation (as originally envisaged in the ICAO Category definitions) had diminished, as clean-air laws had reduced the adverse effect of smoke adding to radiation fog in the worst affected areas. Improved avionics meant that the technology became cheaper to implement, and manufacturers raised the standard of the "basic" autopilot accuracy and reliability. The result was that on the whole the larger new airliners were now able to absorb the costs of at least Category 2 autoland systems into their basic configuration. Simultaneously, pilot organizations globally were advocating the use of Head Up Display systems primarily from a safety viewpoint. Many operators in non-sophisticated environments without many ILS equipped runways were also looking for improvements. The net effect was pressure within the industry to find alternative ways to achieve low visibility operations, such as a "hybrid" system which used a relatively low reliability autoland system monitored by the pilots via a HUD. Alaska Airlines was a leader in this approach and undertook a lot of development work with Flight Dynamics and Boeing in this respect. A major problem with this approach was that European authorities were very reluctant to certificate such schemes as they undermined the well-proven concepts of "pure" autoland systems. This impasse was broken when British Airways became involved as a potential customer for Bombardier's Regional Jet, which could not accommodate a full Cat 3 autoland system, but would be required to operate in those conditions. By working with Alaska Airlines and Boeing, British Airways technical pilots were able to demonstrate that a hybrid concept was feasible, and although British Airways never eventually bought the regional jet, this was the breakthrough needed for international approval for such systems which meant that they could reach a global market. The wheel turned full circle in December 2006 when London Heathrow