Reading the news of the expectation for future uses of GNSS, it seems that aviation (or flight navigation) will get better positioning system that uses new GNSS features.
See what EU says about it here and here: http://www.egnos-portal.eu/users/aviation .
USA has set up rules for a system that shall transmit data of a flights exact position to a "Next Generation Air Transportation System" that tracks all (larger?) aircrafts.
An example of GNSS use in airports: Alaska Air Traffic Controllers Now Using NextGen GPS Technology to Improve Safety .
The term "Safety of Life" (SoL) comes to play, e.g. as a service provided by the Galileo system.
Signal integrity checks and ways to tell if a satellite or a whole system is transmitting reliable data, makes it possible for a GNSS receiver to tell the user (e.g a pilot) when the calculated position can be trusted. When a GNSS system and its receiver indicates a failure, the user can decide to switch to a backup system for navigation.
Another term is Receiver Autonomous Integrity Monitoring (RAIM), used for aviation GPS applications.
From the Institute of Navigation at Stanford University, a slide show "Recent Progress on Aviation Integrity" which tells about occasions where GPS have had different kinds of fault that lead to lower performance of the signals from the satellites. It discusses why integrity is important and the augmentation systems that should provide it.
An article (column) in InsideGNSS: It describes "Aviation applications" and GNSS landing systems. The subtitle is "Part I: Hybrid Navigation Techniques and Safety-of-Life Requirements"
The paper "Worldwide Trends in GNSS Development and their Implications for Civil User Performance and Safety" mentions that it will be necessary to have methods in the receivers to determine if a signal from a given satellite is better or worse than other received signals, when trying to improve position accuracy by the use of many visible satellites. Likewise for the way to estimate the ionopheric delay, to determine if a given compensation method hereof makes the final position error smaller or larger.