when emergency occurs vs when an emergency occurs

Some examples from the web:

• The main objective is to provide the best possible response and preparedness when a major emergency occurs.
• So you'll be able to tell precisely where you are when the big emergency occurs.
• I propose today that some financial reserve be provided within the agricultural budget to address such emergency eventualities when they occur.
• Operators should be empowered, and may even have an obligation under other legislation, to apply emergency plans when damage occurs to ensure quick restoration and prevent greater damage.
• Operators should be empowered, and may even have an obligation under other legislation, to apply emergency plans when damage occurs to ensure quick restoration and prevent greater damage.
• When an emergency situation occurs with regard to the appearance or to new developments of a serious communicable disease, the epidemiological surveillance system should be triggered as soon as possible, in order to ensure protection of the population and public health.
• When an emergency situation occurs with regard to the appearance or to new developments of a serious communicable disease, the epidemiological surveillance system should be triggered as soon as possible, in order to ensure protection of the population and the public health.
• Whereas the recent appearance or resurgence of serious communicable diseases has demonstrated that when an emergency situation occurs all necessary information and data gathered in accordance with an agreed methodology must be communicated swiftly to the Commission;
• (16) Whereas the recent appearance or resurgence of serious communicable diseases has demonstrated that when an emergency situation occurs all necessary information and data gathered in accordance with an agreed methodology must be communicated swiftly to the Commission;
• - appoint a passenger registrar responsible for the keeping and the transmission of that information should an emergency occur or in the aftermath of an accident.
• If an in-flight emergency occurs and the situation permits, a commander shall inform the appropriate Air Traffic Services unit of any Dangerous Goods on board.
• Where a major emergency occurs within the Community, a Member State may request assistance through the MIC or directly from the other Member States.
• If an in-flight emergency occurs and the situation permits, a commander shall inform the appropriate air traffic service unit of any dangerous goods on board.
• As soon as an emergency occurs, the information referred to in paragraph 1 shall be supplemented appropriately, having regard to the specific circumstances.
• 2. As soon as a radiological emergency occurs, this information shall be supplemented appropriately, having regard to the specific circumstances.
• Nothing ever happens, and we are back by 2.00am, but, but-but-but, should an emergency occur, this is the number to call.
• Where an emergency occurs within the Community, a Member State may request assistance, which request should be as specific as possible:
• This competence enables the Commission to ensure that Member States first inform the public of potential risks and the steps that should be taken should a radiological emergency occur; and second, adequately control and supervise shipments of radioactive waste.
• any population group for which specific protection measures are taken as soon as a radiological emergency occurs.
• 1. Where an emergency occurs within the Community, a Member State may request assistance, which request should be as specific as possible:

Some examples from the web:

• When an emergency situation occurs with regard to the appearance or to new developments of a serious communicable disease, the epidemiological surveillance system should be triggered as soon as possible, in order to ensure protection of the population and public health.
• When an emergency situation occurs with regard to the appearance or to new developments of a serious communicable disease, the epidemiological surveillance system should be triggered as soon as possible, in order to ensure protection of the population and the public health.
• Whereas the recent appearance or resurgence of serious communicable diseases has demonstrated that when an emergency situation occurs all necessary information and data gathered in accordance with an agreed methodology must be communicated swiftly to the Commission;
• (16) Whereas the recent appearance or resurgence of serious communicable diseases has demonstrated that when an emergency situation occurs all necessary information and data gathered in accordance with an agreed methodology must be communicated swiftly to the Commission;
• In future, therefore, when an outbreak occurs, emergency vaccination with the aim of allowing animals to live for normal further use should no longer be regarded as a last resort for controlling FMD but must be considered as a first-choice option from the outset.
• In future, therefore, when an outbreak occurs, emergency vaccination with the aim of allowing animals to live for normal further use should no longer be regarded as a last resort for controlling FMD but must be considered as a first-choice option from the outset.
• - appoint a passenger registrar responsible for the keeping and the transmission of that information should an emergency occur or in the aftermath of an accident.
• As soon as an emergency occurs, the information referred to in paragraph 1 shall be supplemented appropriately, having regard to the specific circumstances.
• Nothing ever happens, and we are back by 2.00am, but, but-but-but, should an emergency occur, this is the number to call.
• The main objective is to provide the best possible response and preparedness when a major emergency occurs.
• Where an emergency occurs within the Community, a Member State may request assistance, which request should be as specific as possible:
• 1. Where an emergency occurs within the Community, a Member State may request assistance, which request should be as specific as possible:
• If an in-flight emergency occurs and the situation permits, a commander shall inform the appropriate Air Traffic Services unit of any Dangerous Goods on board.
• Where a major emergency occurs within the Community, a Member State may request assistance through the MIC or directly from the other Member States.
• If an in-flight emergency occurs and the situation permits, a commander shall inform the appropriate air traffic service unit of any dangerous goods on board.
• So you'll be able to tell precisely where you are when the big emergency occurs.
• 2. As soon as a radiological emergency occurs, this information shall be supplemented appropriately, having regard to the specific circumstances.
• This competence enables the Commission to ensure that Member States first inform the public of potential risks and the steps that should be taken should a radiological emergency occur; and second, adequately control and supervise shipments of radioactive waste.
• any population group for which specific protection measures are taken as soon as a radiological emergency occurs.
• If an in-flight emergency occurs the commander shall, as soon as the situation permits, inform the appropriate air traffic services unit of any dangerous goods carried as cargo on board the aeroplane as specified in the Technical Instructions.