Smestow Academy in Wolverhampton was given the bottom rung grading following a visit from Ofsted in September.
School bosses said they were disappointed with the grading and the inspectors comments about attendance levels, but that safeguarding training has been stepped up and strategies put in place to ensure special needs pupils were succeeding.
It has undergone a continual decline since joining the University of Wolverhampton Multi-Academy Trust (UWMAT) – now known as the Greenheart Learning Partnership – and has a succession of headteachers.
In the inspection – the Windmill Crescent school's first since the pandemic – inspectors found there was poor attendance from a significant number of pupils.
They said safeguarding arrangements were "not effective", with records not up to date and staff said to "not always know" whether absent vulnerable pupils were safe.
The report said: "Leaders are not taking the rigorous action needed to ensure that pupils identified at risk of harm are kept safe."
It noted the school had been through an "unsettling time" with "many changes in leadership".
"Leaders have not ensured that all teachers have the skills and knowledge to carefully adapt their subject teaching to meet the needs of all pupils," the report said.
"As a result, in some subjects, teachers do not readily identify pupils who do not have the prior knowledge that they need to fully understand new ideas and concepts.
"This means that some pupils find it difficult to learn the intended curriculum."
The report added that the introduction of a new culture for learning had "already had a positive impact on pupils’ behaviour", while the school's 'building people' programme was said to be having a positive impact.
Smestow was rated "inadequate" overall, with behaviour and attitudes and leadership and management given the same bottom rung rating. The quality of education and sixth form provision were given "requires improvement" ratings, while personal development was said to be "good".
Greenheart said in a statement: "The academy is now a place where relationships between staff and pupils are respectful. Bullying is not a concern for our pupils’ and they feel safe in a school where discrimination is not tolerated.
"We are also pleased that pupils with special educational needs have strategies identified to help them succeed and we will support academy leaders to ensure this is utilised in lessons.
"We have put in significant support and training for staff on safeguarding and have a robust system for documenting concerns, which the report recognises. However, we accept that academy leaders need to do more to interrogate the systems and hold staff to account."
Smestow is in the process of transferring to Matrix Academy Trust (MAT), with current head, Jessie Chahal, understood to be leaving in the new year.