On 19 September 2024, a Boeing 757-200 making its initial descent to San Francisco was approaching its interim cleared level of FL 310 with the seat belt signs having been routinely switched on prior to beginning descent from FL380 when a TCAS ‘CLIMB’ RA was annunciated. The type-inexperienced First Officer’s instant response manoeuvre was abrupt enough to cause serious injury to two unsecured passengers and minor injuries to two other unsecured passengers and two unsecured cabin crew. Flight data showed that a 4½° pitch up had been made within one second resulting in a vertical load factor of over 2g.