The 4th National Audit Project of the Royal College of Anaesthetists' and Difficult Airway Society (NAP4) made recommendations to improve reliability and safety of airway management in hospitals. This survey examines its impact.A survey was sent to all UK National Health Service hospitals to examine changes in practice in response to NAP4. We performed a 'gap analysis' to determine whether NAP4 had reduced the 'safety gap' between actual and ideal practice.The response rate was 62% (192 of 307 hospitals), and 78% answered all questions. Most (97%) respondents reported changes in practice in response to NAP4 but these differed by specialty: 95% in anaesthesia; 80% in intensive care (ICU) and 59% in the emergency department (ED). Approximately 25% reported changes in organizational aspects of airway and human factors teaching. Practice changes led to a median closure of the 'safety gap' in anaesthesia of 39% (IQR 14-66%, range 11-83%), 59% in ICU (IQR 54-73%, range 31-81%) and 48% in ED (IQR 39-53%, range 35-53%).Publication of NAP4 was followed by changes in practice in the majority of responding departments within two yr. Improvements included improved provision of difficult airway equipment and more widespread routine use of capnography. The biggest change occurred in ICU; the impact on training nursing and junior staff was modest and here, significant safety gaps remain.